FORM 4 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
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1. Name and Address of Reporting Person *
Fernandes Prabhavathi
(Last) (First) (Middle)
6320 QUADRANGLE DRIVE
SUITE 360
(Street)
CHAPEL HILL NC 27517
(City) (State) (Zip)
2. Issuer Name and Ticker or Trading Symbol
CEMPRA, INC. [ CEMP ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director 10% Owner
X Officer (give title below) Other (specify below)
President and CEO
3. Date of Earliest Transaction (Month/Day/Year)
05/22/2015
4. If Amendment, Date of Original Filed (Month/Day/Year)
 6. Individual or Joint/Group Filing (Check Applicable Line)
X Form filed by One Reporting Person
Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 05/22/2015   M   13,123 A $ 7.62 232,412 D  
Common Stock 05/22/2015   M   15,266 A $ 13.1 247,678 D  
Common Stock 05/22/2015   M   9,000 A $ 2.09 256,678 D  
Common Stock 05/22/2015   S   9,000 D $ 35.721 (1) 247,678 D  
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year) 7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Employee Stock Option (Right to Buy) $ 23.51               (2) 12/31/2024 Common Stock 133,499   133,499 D  
Employee Stock Option (Right to Buy) $ 1.43               (3) 08/07/2016 Common Stock 12,105   0 D  
Employee Stock Option (Right to Buy) $ 2.47               (4) 06/03/2018 Common Stock 54,273   54,273 D  
Employee Stock Option (Right to Buy) $ 2.09 05/22/2015   M   9,000     (5) 08/09/2019 Common Stock 82,194 $ 0 73,194 D  
Employee Stock Option (Right to Buy) $ 2.09               (6) 07/28/2020 Common Stock 34,133   34,133 D  
Employee Stock Option (Right to Buy) $ 2.09               (7) 12/07/2020 Common Stock 40,698   40,698 D  
Employee Stock Option (Right to Buy) $ 7.62 05/22/2015   M   13,123     (8) 03/19/2022 Common Stock 100,000 $ 0 86,877 D  
Employee Stock Option (Right to Buy) $ 6.63               (9) 01/17/2023 Common Stock 150,000   150,000 D  
Employee Stock Option (Right to Buy) $ 6.64               (10) 03/06/2023 Common Stock 50,000   50,000 D  
Employee Stock Option (Right to Buy) $ 13.1               (11) 01/07/2024 Common Stock 50,000   50,000 D  
Employee Stock Option (Right to Buy) $ 13.1 05/22/2015   M   15,266     (12) 01/07/2024 Common Stock 125,000 $ 0 109,734 D  
Explanation of Responses:
1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $35.60 to $35.92, inclusive.
2. The option vests according to the following schedule: 1/48th of the shares vest at the end of each month over 48 months, beginning after 01/01/2015.
3. The option vested immediately upon its granting on 08/08/06.
4. The option vested according to the following schedule: 1/4th of the shares vest on the one-year anniversary of the 06/03/08 grant date; 1/36th of the remaining shares vest at the end of each month over the next 36 months.
5. The option vests according to the following schedule: 1/4th of the shares vest on the one-year anniversary of the 08/10/09 grant date; 1/36th of the remaining shares vest at the end of each month over the next 36 months.
6. The option vests according to the following schedule: 1/48th of the shares vest at the end of each month over 48 months, beginning 30 days after 04/26/10.
7. The option vests according to the following schedule: 1/48th of the shares vest at the end of each month over 48 months, beginning 30 days after 12/08/10.
8. The option vests in full on 03/20/13.
9. The option vests according to the following schedule: 1/4th of the shares vest on the last day of each quarter after 01/01/2013.
10. The option vests according to the following schedule: 1/4th of the shares vest on the last day of each quarter after 01/01/13.
11. The option vests according to the following schedule: 1/24th of the shares vest monthly at the end of each month over 24 months, beginning on the third anniversary of the Vesting Commencement Date of 01/01/2014.
12. The option vests according to the following schedule: 1/48th of the shares vest at the end of each month over 48 months, beginning after 01/01/2014.
/s/ Alexander M. Donaldson by Power of Attorney 05/27/2015
** Signature of Reporting Person Date
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