CLAIMS

1. A pharmaceutical composition comprising N-acetyl-L-cysteine for use in the treatment of a mammal having endometriosis, characterized in that the composition is for

pulsed or intermittent, oral administration,

for a time period of two months or more,

at a dose of N-acetyl-L-cysteine that is between 20 and 90 mg/kg/day on administration days.

A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to the previous claim, characterized in that it is for administration for 3-5 consecutive days followed by 2-4 days of interruption.

A pharmaceutical composition comprising N-acetyl-L-cysteine for use according claim 1, characterized in that it is for administration for 1-3 consecutive days, followed by 1-2 days of interruption.

A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims, characterized in that it is for administration at a dose of N- acetyl-L-cysteine that is between 30 and 60 mg/kg/day on administration days.

A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims, characterized in that it is for administration at a dose of N- acetyl-L-cysteine that is between 30 and 45 mg/kg/day on administration days.

A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims, characterized in that it is protected from light.

7. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims, characterized in that it is a water soluble tablet.

8. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims, characterized in that it contains sodium hydrogen carbonate.

9. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to claims 1-6, characterized in that it comprises a formulation for slow-release and/or gastric protection.

10. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims in treating pain caused by endometriosis.

11. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims in treating infertility caused by endometriosis.

12. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims in pre-treating mammals having endometriosis before laparoscopy or surgery.

13. A pharmaceutical composition comprising N-acetyl-L-cysteine for use according to any of the previous claims in treatment after laparoscopy or surgery, to prevent recurrences of endometriotic lesions.

14. A method for the treatment of a mammal having endometriosis, comprising orally administering a pharmaceutical composition comprising N-acetyl-L-cysteine to said mammal

in a pulsed or intermittent dosage regimen,

for a time period of two months or more,

at a dose of N-acetyl-L-cysteine that is between 20 and 90 mg/kg/day on administration days.

15. A method according to claim 14, wherein the pharmaceutical composition is administered for 3-5 consecutive days followed by 2-4 days of interruption.

16. A method according to claim 14, wherein the pharmaceutical composition is

administered for 1-3 consecutive days, followed by 1-2 days of interruption.

17. A method according to any of claims 14-16, where the dose of N-acetyl-L-cysteine is between 30 and 60 mg/kg/day on administration days.

18. A method according to any of claims 14-17, where the dose of N-acetyl-L-cysteine is between 30 and 45 mg/kg/day on administration days.

19. A method according to any of claims 14-18, for treating pain caused by endometriosis.

20. A method according to any of claims 14-19, for treating infertility caused by

endometriosis.

21. A method according to any of claims 14-20, for pre-treating mammals having

endometriosis before laparoscopy or surgery.

22. A method according to any of claims 14-21, for treatment after laparoscopy or

surgery, to prevent recurrences of endometriotic lesions.