EXHIBIT 4.7


                            The Tail Wind Fund, Ltd.
                               404 East Bay Street
                        P.O. Box SS 5539, Nassau, Bahamas
                        Fax: 242 393 9021 - attn N Rolle
                     Cc: 011 44 207 468 7657 - attn D Crook

                                October 25, 2001

Fonar Corporation
110 Marcus Drive
Melville, New York 11747

Attn: Raymond Damadian, M.D., President

     Re:  4% Convertible  Debenture Due June 30, 2002 of Fonar  Corporation (the
          "Company")  issued on May 24, 2001 to The Tail Wind Fund,  Ltd. ("Tail
          Wind") in the aggregate  original  principal amount of $4,500,000 (the
          "Debenture");  capitalized terms used herein and not otherwise defined
          shall have the meanings set forth in the Debenture.

Dear Mr. Damadian:

As you are aware,  the Company's second Repayment Date of a Monthly Amount under
the Debenture was originally due on Monday,  October 1, 2001, but such Repayment
Date was extended  until Monday,  October 15, 2001 pursuant to the terms of that
certain  waiver and  modification  letter  dated  October 3, 2001.  Such  second
Monthly  Amount  due has not yet  been  received  by  Tail  Wind,  and you  have
requested that we permit the second  Repayment Date to be further extended until
Monday,  November 5, 2001 and that we also extend the third Repayment Date under
the  Debenture  until  Monday,  November 5, 2001.  We are willing to permit such
extensions on the following terms:

     1.   Each of the Monthly  Amounts  under the  Debenture  originally  due on
          October 1, 2001 and November 1, 2001,  respectively,  shall be paid in
          accordance with the terms of the Debenture on Monday, November 5, 2001
          (which shall constitute a Repayment Date thereunder), provided that if
          the  Company  elects  or is  required  to pay  either  or both of such
          Monthly  Amounts on such  Repayment  Date in shares of Common Stock as
          permitted by and in accordance  with the terms of the Debenture,  then
          (a) the  number of shares to be  issued  in  payment  of such  Monthly
          Amount shall be  determined  by dividing  such  Monthly  Amount by the
          average of the two (2) lowest  closing bid prices of the Common  Stock
          on the Principal  Market during the calendar month of October 2001 (as
          appropriately   and  equitably   adjusted  for  stock  splits,   stock
          dividends,  distributions  and similar events) less $0.25, and (b) the
          Company shall cause its transfer agent to electronically transmit such
          shares by  crediting  the account of Tail Wind's prime broker with DTC
          through  its  Deposit  Withdrawal  Agent  Commission  system  on  such
          Repayment Date or to issue an unlegended stock  certificate which must
          be received by Tail Wind on such Repayment Date. If the Company elects
          or is required to pay either or both of such  Monthly  Amounts on such
          Repayment  Date in cash,  then such  cash  shall be  received  by wire
          transfer  to the  account  of Tail Wind on or prior to such  Repayment
          Date.

     2.   Upon any acceleration of the Debenture  pursuant to the terms thereof,
          such Monthly Amounts shall  automatically  become  immediately due and
          payable.

     3.   Any liquidated damages would be payable in cash immediately,  provided
          that no Default  Interest  or  damages  shall  accrue on such  Monthly
          Amount provided payment is made on November 5, 2001 as provided herein
          (but regular interest shall accrue).

Please be advised that, except for the foregoing waiver and  modification,  this
letter shall not in any way waive or prejudice any of the rights of Tail Wind or
obligations of the Company under the Debenture or other Agreements, or under any
law,  in  equity  or  otherwise,  and such  waiver  and  modification  shall not
constitute a waiver or  modification  of any other provision of the Debenture or
other  Agreements  nor a waiver or  modification  of any  subsequent  default or
breach of any obligation of the Company or of any subsequent  right of Tail Wind
(including  without  limitation  the  payment of all  future  and prior  Monthly
Amounts on the applicable  Repayment Dates in accordance with the Debenture,  as
modified by the prior waiver  between the  parties).  The  foregoing  waiver and
modification  shall  supercede the waiver and  modification  between the parties
dated October 3, 2001. For clarification  purposes,  Tail Wind shall be under no
obligation to, and the Company  acknowledges  that Tail Wind does not intend to,
grant  any  further  waivers  of any  of the  Company's  obligations  under  the
Debenture.

If the foregoing  waiver and  modification is acceptable to the Company,  please
agree to such waiver and  modification  by executing a copy of this letter below
and delivering it to Tail Wind at the above address with a copy to Peter Weisman
at facsimile  number  (212)  986-8866.  This letter  shall not become  effective
unless and until it is duly executed and delivered by the Company, at which time
it shall become binding and enforceable  against both the Company and Tail Wind.
This letter  shall  remain  revocable  by Tail Wind until it is so executed  and
delivered by the Company.


                                                     Very truly yours,

                                                     THE TAIL WIND FUND, LTD.


                                                     By: /s/Ngaire Rolle
                                                     Ngaire Rolle
AGREED AND ACCEPTED:

FONAR CORPORATION

By: /s/ Raymond Damadian
Raymond Damadian, M.D., President