Exhibit 5.1

                               LATHROP & GAGE L.C.
                                   LAW OFFICES
2345 Grand Boulevard                           1050/40 Corporate Woods
Suite 2800                                     9401 Indian Creek Parkway
Kansas City, Missouri 64108-2684               Overland Park, Kansas 66210-2007
816-292-2000, Fax 816-292-2001                 913-451-5100, Fax 913-451-0875

                                 JOHN H. CALVERT
                                  816-460-5807
              jcalvert@lathropgage.com or 72741.3656@compuserve.com

                                  _______, 1999

Board of Directors
Lab Holdings, Inc.
5000 West 95th Street
Shawnee Mission, Kansas 66207

     Re:  Offering by Lab  Holdings,  Inc.  (the  "Company") of shares of Common
Stock,  $0.01 par value (the "Common Stock") pursuant to that certain  Agreement
and Plan of Merger by and between Lab Holdings, Inc. and LabOne, Inc. as amended
and  restated,  dated as of March 7, 1999 (the  "Merger  Agreement"),  a copy of
which is appended to the Joint  Proxy  Statement/Prospectus  that has been filed
with  the  Securities  and  Exchange  Commission  as a part of the  registration
statement  of the Company on Form S-4,  file No.  333-_____  (the  "Registration
Statement").

Gentlemen,

         We have acted as counsel to the  Company in  connection  with the above
referenced  Offering  pursuant to which the Company  proposes to issue shares of
its Common  Stock to the holders of common stock of LabOne,  Inc. in  accordance
with the terms of the Merger Agreement.

         We have examined the Merger  Agreement,  the Articles of  Incorporation
and Bylaws of the Company, as amended, the proceedings of the Board of Directors
of the Company in connection with the  authorization,  execution and delivery of
the Merger Agreement and the filing of the Registration Statement,  certificates
of officers of the Company and of state officials and such other documents as we
have deemed  necessary  in order to express  the  opinion set out herein.  As to
certain questions of fact material to our opinion we have,  without  independent
investigation,  relied upon the representations and warranties of the parties as
set forth in the Merger  Agreement.  We have also assumed the genuineness of all
signatures on original documents and certificates examined by us.

         Our opinion is limited to the matters  expressly set forth herein,  and
no opinion is to be implied or may be inferred  beyond the matters  expressly so
stated.  Our  opinion is also  limited to the effect of the laws of the state of
Missouri and the Federal laws of the United  States.  We express no opinion with
respect  to the  effect of the laws of any  other  jurisdiction  on the  matters
referred to herein.  We further  disclaim any  obligation to update this opinion
letter for events occurring after the date of this opinion letter.

         Based upon the foregoing, and assuming that (i) the Merger Agreement is
approved by the holders of the  requisite  number of shares of capital  stock of
the parties thereto, (ii) that all conditions to the Merger Agreement are either
satisfied or properly  waived,  and (iii) that the Merger  Agreement is properly
filed with and  certificates  of merger with respect  thereto are duly issued by
the  Secretaries of State of Missouri and Delaware,  all as  contemplated by the
Merger  Agreement,  we are of the opinion that the Common Stock,  when issued to
the
                       


Board of Directors
Lab Holdings, Inc.
______________, 1999
Page 2


stockholders  of  LabOne  pursuant  to  the  Merger  Agreement,   will  be  duly
authorized, legally issued, fully paid and non-assessable.

         We consent to the use of this opinion in the Registration Statement and
in pre-effective and post-effective  amendments  thereto. We also consent to the
use of this opinion and to the  reference to our firm under the caption  ("Legal
Opinions") in the Joint Proxy Statement/Prospectus of the Registration Statement
and amendments thereto.

                                           Very truly yours,

                                           LATHROP & GAGE L.C.

                                      
                                       By:  
                                           John H. Calvert