This study was designed as a proof-of-concept trial to evaluate safety, tolerability, and the efficacy of 1800 mg (ZK 811752 600 mg given orally three times daily) over 12 weeks for the treatment of endometriosis associated pelvic pain (EAPP) in comparison to placebo.

The study has previously been posted by Schering AG, Germany. Schering AG, Germany has been renamed to Bayer Schering Pharma AG, Germany.

Bayer Schering Pharma AG, Germany is the sponsor of the trial.

Inclusion Criteria:

• Pain associated with proven endometriosis, as determined by diagnostic measures within 24 months prior to start of treatment
• Women with cyclic menstrual bleeding- Good general health
• Willingness to use a barrier contraceptive method such as condoms but no hormonal contraception- Willingness to use only up to 3 Ibuprofen 400 tablets as pain killer for endometriosis-related pelvic pain - Age 18 to 45 years inclusive - Fertile and non-fertile Exclusion Criteria:
• Pregnancy, lactation- Bearing of an intra-uterine device
• Current use of hormonal agents.
• Actual or history of cardiovascular and further serious disorders