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                                                                   EXHIBIT 10.39

                                 PROMISSORY NOTE

$90,000.00                                                   Fort Myers, Florida
                                                             September 16, 1993

         FOR VALUE RECEIVED, CENTRAL RADIATION THERAPY INSTITUTE, P.A. a Florida
Professional Association, promises to pay to the order of NATALIE J. DRIGGERS
the principal sum of NINETY THOUSAND. ($90,000.00) DOLLARS, plus interest
thereon at the prime rate, said principal and interest being payable in lawful
money of the United States to Natalie J. Driggers, in care of Brenda Sheridan,
at 842 Cal Cove Drive, Fort Myers, Florida 33919, or at such other place as the
holder thereof may designate in writing,

         This is a Demand Note.

         If Holder of the note demands payment of the note, holder must notify
Central Radiation Therapy Institute, P.A. at 920 Mills Avenue Arcadia, Florida
33821 by certified mail, return receipt requested, that the entire remaining
unpaid principal balance plus any accrued interest must be paid in full within
sixty (60) days from the date of the letter demanding full payment. Only
interest payments will be required at the prime rate of interest which shall be
paid on October 16, 1993 and on the 16th day of each month thereafter until a
demand is made for the payment of the remaining unpaid principal balance and
accrued interest. Interest shall be paid at the prime rate established by
Nations Bank of Florida, N.A. in Tampa, Florida.

         1. Prime Rate: For purposes hereof, "Prime Rate" means the fluctuating
rate of interest per annum established by Nations Bank of Florida, N.A. ("Bank")
in Tampa, Florida as its prime lending rate in effect from time to time whether
or not such rate shall be otherwise published. Such Prime Rate is established by
Bank as an index or base rate.

         2. Interest: The outstanding loan principal balance shall bear interest
at a variable rate per annum, equal to the Prime Rate. The interest rate
hereunder shall be adjusted daily in accordance with fluctuations in the Prime
Rate. Interest shall be computed on the basis of a daily amount of interest
accruing on the daily outstanding principal balance during a 360 day year
multiplied by the actual number of days the principal is outstanding during such
applicable interest period.

         The maker may pay all or part of the principal balance outstanding plus
accrued interest, before due, without payment of any penalty.

         Each maker and endorser severally waives demand, protest and notice of
maturity, nonpayment or protest and all requirements necessary to hold each of
than liable as makers and endorsers.

         Each maker and endorser further agrees, jointly and severally, to pay
all costs of collection, including a reasonable attorneys fee in case the
principal and interest of this note or any payment on the principal and interest
thereon is not paid at the respective maturity thereof, or in case it becomes
necessary to protect the security hereof, whether suit be brought or not.

         If any installment of principal or interest is not made within 15 days
from the date it is due, the entire remaining, unpaid principal balance, plus
accrued interest shall become immediately due and payable in full, at the option
of the holder of the note. Holder of note has the right to accelerate the
remaining unpaid principal balance and accrued interest.

         This note is governed by the Laws of the State of Florida.

         This note is binding on the heirs, personal representatives, assigns,
transferees of the parties hereto.

Address of Maker:                                 CENTRAL RADIATION THERAPY
920 North Mills Avenue                            INSTITUTE, P.A.
Arcadia, FL
                                                  BY: /s/ Daniel E. Dosoretz
                                                      ----------------------
                                                  DANIEL E. DOSORETZ, M.D.
                                                  Secretary and Chief Executive
                                                  Officer<PAGE>

                                                                   EXHIBIT 10.40

                                 PROMISSORY NOTE

$100,000.00                                                  Fort Myers, Florida
                                                             May 4, 1993

         FOR VALUE RECEIVED, KATIN, DOSORETZ, RADIATION THERAPY ASSOCIATES,
P.A., a Florida Professional Association, promises to pay to the order of
NATALIE J. DRIGGERS the principal sum of ONE HUNDRED THOUSAND ($100,000.00)
DOLLARS, plus interest thereon at the prime rate, said principal and interest
being payable in lawful money of the United States to Natalie J. Driggers, in
care of Brenda Sheridan, at 842 Cal Cove Drive, Fort Myers, Florida 33919, or at
such other place as the holder thereof may designate in writing.

         This is a Demand Note.

         If Holder of the note demands payment of the note, holder must notify
Katin, Dosoretz, Radiation Therapy Associates, P.A, at 3680 Broadway, Fort
Myers, Florida 33901, by certified mail, return receipt requested, that the
entire remaining unpaid principal balance plus any accrued interest must be paid
in full within sixty (60) days from the date of the letter demanding full
payment. Only Interest payments will be required at the prime rate of interest
which shall be paid on June 4, 1993 and on the 4th day of each month thereafter
until a demand is made for the payment of the remaining unpaid principal balance
and accrued interest. Interest shall be paid at the prime rate established by
Nations Bank of Florida, N.A. in Tampa, Florida.

         1. Prime Rates: For purposes hereof, "Prime Rate" means the fluctuating
rate of interest per annum established by Nations Bank of Florida, N.A. ("Bank")
in Tampa, Florida as its prime lending rate in effect from time to time whether
or not such rate shall be otherwise published. Such Prime Rate is established by
Bank as an index or base rate.

         2. Interest: The outstanding loan principal balance shall bear interest
at a variable rate per annum, equal to the Prime Rate. The interest rate
hereunder shall be adjusted daily in accordance with fluctuations in the Prime
Rate. Interest shall be computed on the basis of a daily amount of interest
accruing on the daily outstanding principal balance during a 360 day year
multiplied by the actual number of days the principal is outstanding during such
applicable interest period.

         The maker may pay all or part of the principal balance outstanding plus
accrued interest, before due, without payment of any penalty.

         Each maker and endorser severally waives demand, protest and notice of
maturity, nonpayment or protest and all requirements necessary to hold each of
than liable as makers and endorsers.

         Each maker and endorser further agrees, jointly and severally, to pay
all costs of collection, including a reasonable attorneys fee in case the
principal and interest of this note or any payment on the principal and interest
thereon is not paid at the respective maturity thereof, or in case it becomes
necessary to protect the security hereof, whether suit be brought or not.

         If any installment of principal or interest is not made within 15 days
from the date it is due, the entire remaining unpaid principal balance, plus
accrued interest shall became immediately due and payable in full, at the option
of the holder of the note. Holder of note has the right to accelerate the
remaining unpaid principal balance and accrued interest.

         This note is governed by the Laws of the State of Florida.

         This note is binding on the heirs, personal representatives, assigns,
transferees of the parties hereto.

Address of Maker:                                KATIN, DOSORETZ RADIATION
3680 Broadway                                    THERAPY ASSOCIATES, P.A.
Fort Myers, FL 33901
                                                 By : /s/ Daniel E. Dosoretz
                                                     ---------------------------
                                                 DANIEL E. DOSORETZ, M.D.
                                                 Secretary and Chief Executive
                                                 Officer<PAGE>

Kadash Partnership
2234 Colonial Blvd.
Ft. Myers, Florida 33907
Att: Cathy Newkirk

                                                                   EXHIBIT 10.41

                                 PROMISSORY NOTE

$320,000.00                       Miami, Florida         Date: December 28, 1999

         FOR VALUE RECEIVED the undersigned promises to pay to the order of
RADIATION CENTERS OF AMERICA INC. the principal sum of Three Hundred Twenty
Thousand Dollars and no cents ($320,000.00), together with interest thereon, at
the prime rate (which shall be determined on a monthly basis) until maturity,
principal and interest being payable in lawful money of the United States or its
equivalent, at such place as the holder may designate in writing, said principal
sum to be payable on the dates and in the amounts specified below, to wit:

         Monthly payments of principal and interest in the amount of Ten
thousand one hundred one $ & 64 cents shall be paid on the first day of
February,2000 and a like amount on the first day of each and every month
thereafter for thirty six (36) months at which time all accrued interest and
principal shall be paid in full. Prepayments may be made at any time without
premium or penalty.

         In the event payment of interest and principal is not paid within
fifteen (15) days of the due date, the maker will incur a late charge of ten
(10%) percent of the amount due. Any such late charge will be due and payable
with the next regular monthly payment. If any such late charge is not paid at
that time, the late charge amount shall be added to the outstanding principal
and interest shall be charged thereon from the late-charge due date.

         Each maker and endorser severally waives demand, protest and notice of
maturity, non-payment or protest and all requirements necessary to hold each of
them liable as makers and endorsers.

         Each maker and endorser further agrees, jointly and severally, to pay
all costs of collection, including a reasonable attorney's fee in case the
principal of this note or any payment on the principal or any interest thereon
is not paid at the respective maturity thereof, or in case it becomes necessary
to protect the security hereof, whether suit be brought or not.

         This note and deferred interest payments shall bear interest at the
highest rate allowable by law per annum from maturity until paid.

                                            21st Century Oncology Inc.

                                            By: /s/ Herbert Ort
                                                ----------------------------
                                                Herbert Ort, Treasurer

Payable at:                            * adjusted monthly as prime rate changes.
3511, West Commercial Blvd.
Ft. Lauderdale, FL 33309

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