THESE  SECURITIES HAVE NOT BEEN  REGISTERED  UNDER THE SECURITIES ACT OF 1933 OR
ANY STATE  SECURITIES  ACTS OR LAWS,  AND HAVE BEEN  ISSUED AND SOLD IN RELIANCE
UPON  EXEMPTIONS  FROM THE  REGISTRATION  REQUIREMENTS  OF SUCH  ACTS AND  LAWS,
INCLUDING  BUT NOT LIMITED TO THE  EXEMPTION  CONTAINED  IN SECTION  4(2) OF THE
SECURITIES ACT OF 1933. THESE SECURITIES MAY NOT BE SOLD OR TRANSFERRED UNLESS A
REGISTRATION  STATEMENT  HAS BECOME AND IS THEN  EFFECTIVE  WITH RESPECT TO SUCH
SECURITIES   OR  CRYOLIFE  HAS   RECEIVED  AN  OPINION  OF  COUNSEL   REASONABLY
SATISFACTORY TO ITS COUNSEL, TO THE EFFECT THAT THE PROPOSED SALE OR TRANSFER IS
EXEMPT FROM  REGISTRATION  UNDER THE  SECURITIES  ACT OF 1933 AND ALL APPLICABLE
STATE SECURITIES ACTS AND LAWS.


                       SUBORDINATED CONVERTIBLE DEBENTURE
                                       OF
                                 CRYOLIFE, INC.

$4,999,999                                                        MARCH 5, 1997

     CRYOLIFE,  INC., a Florida  corporation  ("CryoLife"),  for value received,
hereby  promises  to pay to the order of J.  Crayton  Pruitt,  Sr.,  M.D. or his
permitted  assigns  (the  "Holder")  at 643 6th Avenue  South,  St.  Petersburg,
Florida  33701,  the sum of  $4,999,999,  plus interest on the unpaid  principal
balance at the rate specified below, in accordance with the provisions set forth
herein. During the term of this Debenture,  interest shall accrue at the rate of
7% per annum,  compounded annually.  Accrued interest shall be payable quarterly
in arrears on each March 31, June 30, September 30, and December 31 of each year
in which any principal  payable  hereunder is  outstanding.  The full  principal
amount of this Debenture,  including any accrued interest thereon,  shall be due
and payable on the fifth anniversary of the date hereof.

     The following is a statement of the rights of the Holder and the conditions
to which this  Debenture  is  subject,  and to which the Holder  hereof,  by the
acceptance of this Debenture, agrees:

     1. Prepayment.

         1.1 Right to Prepay. At, or at any time after, March 5, 2000,  CryoLife
may at any time and from time to time  prepay in whole or in part the  Debenture
(the amount of any prepayment being  hereinafter  referred to as the "Prepayment
Amount"). Any payment made in partial prepayment shall be allocated first to the
payment of accrued interest and then to principal.



394152.8





         1.2 Notice. At least 45 days prior to the date fixed for any prepayment
of the Debenture (the "Prepayment  Date"),  written notice shall be delivered to
the Holder at his address last shown on the records of CryoLife,  notifying  the
Holder of the election of CryoLife to prepay the Debenture, in whole or in part,
and specifying in such notice the Prepayment  Date, the Prepayment  Amount,  the
extent to which the payment of the Prepayment Amount will terminate the Holder's
conversion rights under Section 3 of this Debenture, and calling upon the Holder
to  surrender  to  CryoLife,  in the  manner  and at the place  designated,  his
Debenture certificate (such notice is hereinafter referred to as the "Prepayment
Notice").

         1.3 Surrender of Debenture.  On or prior to the Prepayment Date, unless
Holder shall have  converted the Debenture by providing  notice of conversion at
least ten days before the Prepayment  Date pursuant to the provisions of Section
3 of this Debenture,  the Holder shall surrender his Debenture  certificate,  in
the manner and at the place designated in the Prepayment  Notice,  and thereupon
the  Prepayment  Amount  shall be  payable  to the order of the  Holder  and the
Debenture,  if prepaid in full, shall be canceled. In the event the Debenture is
prepaid in part, the Debenture shall be returned to Holder  appropriately marked
to show partial prepayment and reduction of principal.

     2.  Events of Default.  If any of the events  specified  in this  Section 2
shall occur (an "Event of Default"),  the entire  principal  and unpaid  accrued
interest  hereon  shall become  immediately  due and payable if the Holder gives
notice to CryoLife of its election to declare a default hereunder as a result of
any of the following:

         (i) CryoLife fails to pay the unpaid  principal and accrued interest on
any date  due,  and does not cure such  failure  within  30 days of  receipt  of
written notice of such nonpayment; or

         (ii) CryoLife makes an assignment for the benefit of creditors,  or any
proceeding is instituted by or against CryoLife  alleging that it is bankrupt or
insolvent;  provided however,  that if any such proceeding is instituted against
CryoLife by a third party,  such event shall not  constitute an Event of Default
if dismissed within 90 days.

     3. Conversion.

         3.1 Election by Holder. The Holder has the right, at any time after the
first  anniversary  of this  Debenture  and until March 5, 2002, to convert this
Debenture in accordance  with the provisions of Subsection 3.2 hereof,  in whole
or in part,  into fully  paid and  nonassessable  shares of the Common  Stock of
CryoLife (the "Common  Stock").  The number of shares of Common Stock into which
this  Debenture  may be  converted  at any given  time  shall be  determined  by
dividing the sum of the unpaid principal amount by the Conversion Price. As used
herein,  the term  "Conversion  Price"  shall  mean a price of $12.08 per share,
which represents the average of the daily closing bid/ask price for CryoLife


394152.8

                                       -2-





Common Stock reported on the Nasdaq Stock Market's  National  Market as reported
in The Wall Street Journal newspaper for the period ending 90 days preceding the
last day of the week  immediately  preceding the date hereof,  which  Conversion
Price  shall be subject to  adjustment  as set forth in Section 4.  Accrued  but
unpaid  interest on the  converted  principal  shall become due and payable upon
such conversion.

         3.2  Conversion  Procedure.  Before the  Holder  shall be  entitled  to
convert this  Debenture  into shares of Common Stock,  it shall  surrender  this
Debenture  at the  office of  CryoLife  and shall  give ten days  prior  written
notice,  to CryoLife  at its  principal  corporate  office,  of the  election to
convert the same  pursuant to this  Subsection  3.2, and shall state therein the
name or names in which the certificate or  certificates  for the shares issuable
upon such conversion (the "Conversion Shares") are to be issued. CryoLife shall,
as soon as practicable thereafter, issue and deliver to the Holder a certificate
or certificates for the number of Conversion Shares to which the Holder shall be
entitled. Such conversion shall be deemed to have been made immediately prior to
the close of business on the date of such  surrender of this  Debenture  and the
receipt of the notice  required  herein,  and the person or persons  entitled to
receive the  Conversion  Shares  shall be treated for all purposes as the record
holder or holders of such Conversion Shares as of such date and shall be payable
within ten days following such date.

         3.3 No Fractional Shares. No fractional shares of Common Stock shall be
issued  upon  conversion  of this  Debenture.  In lieu of  CryoLife  issuing any
fractional shares to the Holder upon the conversion of this Debenture,  CryoLife
shall pay to the Holder in immediately available funds the amount of outstanding
principal  that is not so converted.  Upon  conversion of this Debenture and the
proper  issuance of the Conversion  Shares,  CryoLife shall be forever  released
from all its obligations and liabilities under this Debenture.

     4. Conversion Price Adjustments.

         4.1  Adjustments  for  Stock  Splits  and  Subdivisions.  In the  event
CryoLife  should  at any time or from time to time  after  the date of  issuance
hereof fix a record date for the  effectuation  of a split or subdivision of the
outstanding  shares of Common  Stock or the  determination  of holders of Common
Stock entitled to receive a dividend or other distribution payable in additional
shares of  Common  Stock or other  securities  or rights  convertible  into,  or
entitling  the holder  thereof to receive  directly  or  indirectly,  additional
shares of Common Stock (hereinafter  referred to as "Common Stock  Equivalents")
without payment of any consideration by such holder for the additional shares of
Common Stock or the Common Stock Equivalents (including the additional shares of
Common Stock  issuable upon  conversion or exercise  thereof),  then, as of such
record date (or the date of such dividend distribution,  split or subdivision if
no record  date is  fixed),  the  Conversion  Price of this  Debenture  shall be
appropriately  decreased so that the number of shares of Common  Stock  issuable
upon  conversion  of this  Debenture  shall be increased in  proportion  to such
increase of outstanding  shares.  If the Conversion Price is adjusted under this
Section 4.1 but


394152.8

                                       -3-





the dividend  distribution,  split or  subdivision  which was the basis for such
adjustment is ultimately abandoned by CryoLife,  then the Conversion Price shall
be readjusted to offset the effect of such previous adjustment.

         4.2  Adjustments  for Reverse Stock Splits.  If the number of shares of
Common  Stock  outstanding  at any time after the date hereof is  decreased by a
combination  of the  outstanding  shares of Common  Stock,  then,  following the
record date of such  combination,  the Conversion Price for this Debenture shall
be appropriately increased so that the number of shares of Common Stock issuable
on  conversion  hereof  shall be  decreased in  proportion  to such  outstanding
shares.

         4.3  Reservation of Stock Issuable upon  Conversion.  CryoLife shall at
all times reserve and keep available out of its  authorized but unissued  shares
of Common  Stock such number of its shares of Common Stock as shall from time to
time be sufficient to effect the full conversion of the Debenture.

     5. Subordination.

         5.1 Agreement to  Subordinate.  Notwithstanding  anything  contained in
this Debenture to the contrary,  CryoLife hereby covenants and agrees,  and each
holder hereof, by its acceptance thereof, likewise covenants and agrees that the
indebtedness  evidenced  by this  Debenture  and the  payment  of the  principal
thereof  and  interest  thereon  and  all  other  amounts  payable  under  or in
connection  with  this  Debenture  (the  "Subordinated  Indebtedness")  shall be
subordinate  and  subject in right of  payment,  to the extent and in the manner
hereinafter set forth, to the prior indefeasible  payment in full in cash of all
Senior Indebtedness (as hereinafter defined), and that such subordination is for
the benefit of the holders of Senior Indebtedness.

         5.2 Distribution on Dissolution,  Etc. In the event of any voluntary or
involuntary insolvency or bankruptcy proceedings or any voluntary or involuntary
receivership,  liquidation,  reorganization  or  other  similar  proceedings  in
connection therewith,  relative to CryoLife or to its creditors,  as such, or to
all or any part of its property, or in the event of any voluntary or involuntary
proceedings for liquidation,  dissolution or other winding up of CryoLife or any
assignment   for  the  benefit  of  creditors  or   marshalling  of  assets  and
liabilities, whether or not involving insolvency or bankruptcy, then the holders
of Senior  Indebtedness  shall be entitled to receive payment in full in cash of
the principal of and the premium,  if any, and interest on and all other amounts
constituting Senior Indebtedness before the holder of this Debenture is entitled
to receive payment or distribution,  direct or indirect, of or on account of the
principal  of,  premium,  if any,  or interest  on this  Debenture  or any other
Subordinated Indebtedness in cash or property (whether by payment,  acquisition,
retirement,  defeasance, redemption or otherwise) and to that end the holders of
Senior  Indebtedness,  until payment in full in cash of the principal of and the
premium,  if  any,  and  interest  on  and  other  amounts  constituting  Senior
Indebtedness,  shall be entitled to receive any payment or  distribution  of any
kind or character, whether in cash, securities or


394152.8

                                       -4-





other  property,  which  may be  payable  or  deliverable  in  respect  of  this
Debenture,  including any such payment or  distribution  which may be payable or
deliverable by virtue of any security for, or by virtue of the provisions of (or
any security for) any securities  which are  subordinate  and junior in right of
payment to, this Debenture.

         5.3 Default on Senior Indebtedness.

              5.3.1 Payment Defaults.  Neither CryoLife nor any person on behalf
of CryoLife shall,  directly or indirectly,  make any payment or distribution on
account  of the  principal  of or  interest  on  this  Debenture  or  any  other
Subordinated   Indebtedness  (whether  by  payment,   acquisition,   retirement,
defeasance, redemption or otherwise) in cash or property during the existence of
a  default  in the  payment  when  due  (whether  at  stated  maturity  or  upon
acceleration  or mandatory  prepayment or on any principal  installment  payment
date or interest  payment  date, or  otherwise)  of any Senior  Indebtedness  (a
"Payment  Default")  until the earlier of (i) the date such  Payment  Default is
cured (if capable of being  cured) or waived in writing in  accordance  with the
terms  of such  Senior  Indebtedness,  and (ii)  the  date  application  of this
subsection   5.3.1  has  been  waived  in  writing  by  all  holders  of  Senior
Indebtedness  (or the trustee or agent on behalf of such  holders) in accordance
with the terms of the  agreements  or other  documents  evidencing  such  Senior
Indebtedness.

              5.3.2  Non-Payment  Defaults.  Neither  CryoLife nor any person on
behalf  of  CryoLife  shall,  directly  or  indirectly,   make  any  payment  or
distribution on account of the principal of or interest on this Debenture or any
other Subordinated  Indebtedness (whether by payment,  acquisition,  retirement,
defeasance,  redemption or  otherwise) in cash or property  during the period (a
"Deferral Period") from the date CryoLife receives from any holder or holders of
Senior  Indebtedness (or a trustee or agent on behalf of such holder or holders)
in accordance with the terms of such  agreements or other  documents  evidencing
such Senior Indebtedness, a notice of the existence of any default (other than a
Payment  Default)  with  respect  to any  Senior  Indebtedness  (a  "Non-Payment
Default") until the earliest of (i) the date such  Non-Payment  Default is cured
(if capable of being cured) or waived in writing in accordance with the terms of
such Senior Indebtedness, and (ii) the date application of this subsection 5.3.2
has been waived in writing by all holders of Senior Indebtedness (or the trustee
or agent  on  behalf  of such  holders)  in  accordance  with  the  terms of the
agreements or other documents evidencing such Senior Indebtedness.

         5.4 Subordination  Not Impaired.  No present or future holder of Senior
Indebtedness  shall be prejudiced in its right to enforce  subordination of this
Debenture by any act or failure to act on the part of CryoLife or by its failure
to  comply  with this  Debenture,  or by any act or  failure  to act by any such
holder  of  Senior   Indebtedness   undertaken  in  good  faith.  The  foregoing
subordination  provisions  shall be for the  benefit  of all  holders  of Senior
Indebtedness from time to time outstanding, and each of such holders may proceed
to enforce such provisions  either directly against the holder of this Debenture
or in any other manner provided by law and without the need to prove reliance on
the


394152.8

                                       -5-





subordination  hereof.  As used herein,  the term "holders" of any  indebtedness
shall  include  any  trustee  for, or other  authorized  representative  of, the
holders of such indebtedness.

         5.5 Definitions.

         "Leverage  Ratio" shall mean, as of any  particular  date, the ratio of
CryoLife's Total Liabilities to its Net Worth at such date.

         "Net Worth" shall mean, as of any  particular  date,  CryoLife's  total
shareholders's equity (including capital stock,  additional paid in capital, and
retained earnings after deducting  treasury stock) which would appear as such on
a consolidated  balance sheet of CryoLife  prepared in accordance with generally
accepted accounting principles as then in effect.

         "Senior   Indebtedness"  means  (i)  CryoLife's  existing   outstanding
indebtedness and credit facilities (excluding any trade indebtedness) ("Existing
Indebtedness"),  including,  without  limitation,  (A) any and all  obligations,
liabilities  and  indebtedness,   whether  in  respect  of  principal,  interest
(including without limitation  interest accruing after the filing of a petition,
action or  proceeding by or against  CryoLife  pursuant to any  bankruptcy  law,
whether or not the claim for such  interest  would be allowed as a claim in such
proceeding), premium, fees, expenses, reimbursement obligations,  indemnities or
other  amounts,  of  CryoLife,  whether  contingent  or mature,  now existing or
hereafter  arising  or  advanced,  under and  pursuant  to that  certain  Credit
Agreement, dated as of August 30, 1996, by and between CryoLife and NationsBank,
N.A.  (South)  and the other  Financing  Documents  (as  defined in such  Credit
Agreement), and any modifications, renewals, extensions, amendments, supplements
or restatements of any of the foregoing, provided that the outstanding principal
indebtedness  outstanding  thereunder which shall at any time constitute  Senior
Indebtedness  shall not exceed  $10,000,000  (except as  otherwise  provided  in
subsection (ii) below),  (B) that certain  Promissory Note in a principal amount
of $1,250,000 in favor of United Cryopreservation  Foundation, Inc., and (C) any
indebtedness  up to an aggregate  principal  amount of  $11,250,000  incurred by
CryoLife  to replace  the loans  identified  in (A) and (B) or  constituting  an
extension,  refinancing or renewal thereof,  and (ii) any  indebtedness  ("Other
Indebtedness")  of CryoLife  for money  borrowed  from any lender  (except  from
officers or directors of  CryoLife),  created or incurred  after the date hereof
(excluding any Existing Indebtedness);  provided, however, that the portion (and
only such  portion)  of Other  Indebtedness  that,  when  added to the  Existing
Indebtedness then in effect, causes the Leverage Ratio to exceed 1.0 to 1.0 (the
"Excess  Indebtedness") shall be in parity to the indebtedness evidenced by this
Debenture.  For example,  assume that CryoLife is seeking a $20,000,000 loan and
that CryoLife  could obtain a $15,000,000  loan and maintain a Leverage Ratio of
1.0 to 1.0,  but any loan  amount  in  excess  of  $15,000,000  would  cause the
Leverage Ratio to exceed 1.0 to 1.0.  CryoLife may obtain the $20,000,000  loan,
provided  $15,000,000 of such loan shall be Senior  Indebtedness  and $5,000,000
shall be  repayable  by  CryoLife  on a pari passu  basis with the  indebtedness
evidenced  by this  Debenture.  Excess  Indebtedness  may be  included as Senior
Indebtedness and shall be treated


394152.8

                                       -6-





as  provided  in Section  5.1  through  5.4 upon the consent of the holders of a
majority in interest of the aggregate principal amount of the IFM Debentures (as
defined in Section 7 below), which consent shall not be unreasonably withheld.

         "Total  Liabilities"  shall mean, as of any particular date, the amount
which all liabilities of CryoLife would be shown on a consolidated balance sheet
of  CryoLife  at such  date  prepared  in  accordance  with  generally  accepted
accounting principles consistently applied.

     6. Assignment. Subject to the restrictions on transfer described in Section
8 below,  the rights and obligations of CryoLife and the Holder shall be binding
upon and benefit the successors,  assigns, heirs, administrators and transferees
of the parties.

     7. Waiver and  Amendment.  Any provision of this  Debenture may be amended,
waived or modified only upon the written  consent of CryoLife and the holders of
a majority of the aggregate principal amount of indebtedness  evidenced by those
certain debentures (the "IFM Debentures"), of which this Debenture is one, which
were  issued as part of the  merger of Ideas for  Medicine,  Inc.  with and into
CryoLife  Acquisition  Corporation,   a  wholly-owned  subsidiary  of  CryoLife,
pursuant to that Agreement and Plan of Merger dated March 5, 1997.

     8. Transfer of this  Debenture or Conversion  Shares.  The Holder shall not
make any offer,  sale or other  disposition  of this Debenture or the Conversion
Shares unless the Holder shall first have provided to CryoLife a written opinion
of the Holder's counsel,  reasonably  satisfactory to CryoLife's counsel, to the
effect  that such offer,  sale or other  distribution  may be  effected  without
registration or  qualification  (under any federal or state law then in effect).
If so transferred,  the Debenture or the Conversion Shares, as applicable, shall
bear a legend as to the applicable  restrictions on  transferability in order to
ensure compliance with state and federal  securities laws, unless in the opinion
of  counsel  for  CryoLife  such  legend  is not  required  in order  to  ensure
compliance with such laws.

     9. Notices. All notices, demands or other communications hereunder shall be
in  writing  and shall be deemed  given  when  delivered  personally,  mailed by
certified mail, return receipt requested,  sent by overnight courier service, or
telecopied  (transmission  confirmed  and a  copy  sent  by  personal  delivery,
certified mail or overnight courier service) to the following  addresses or such
other address as may be designated in writing by either party in accordance with
the terms of this provision:

          Holder:  J. Crayton Pruitt, Sr., M.D.
                   643 6th Avenue South
                   St. Petersburg, Florida 33701



394152.8

                                       -7-




        CryoLife:  CryoLife, Inc.
                   1655 Roberts Boulevard, N.W.
                   Kennesaw, Georgia 30144
                   Attention:  President and Chief Executive Officer
                   Telefax: (770) 426-0031

     IN WITNESS  WHEREOF,  CryoLife  has caused  this  Subordinated  Convertible
Debenture to be issued as of the date first set forth hereinabove.

                     CRYOLIFE, INC.


                      By:__________________________________
                          Edwin B. Cordell, Jr.
                          Vice President of Finance and
                          Chief Financial Officer





394152.8

                                       -8-