The objective of this study is to determine the long-term safety of asoprisnil 5 mg for 12 months in women with endometriosis from study M01-398.

Endometriosis, the presence of endometrial tissue outside the uterus, is a progressive, estrogen-dependent disease that occurs in menstruating women of reproductive age. Although all major endometriosis therapies are effective for the treatment of pain, no single treatment is superior to others in terms of efficacy. The major drawbacks of the current medical therapies are severe side effects such as hot flushes and osteoporosis. The objective of this study is to determine the long-term safety of asoprisnil 5 mg daily for 12 months in women with endometriosis, after an initial 12 weeks in study M01-398. The safety will be based on assessments of the endometrium, lipid profiles, adverse events, and changes from baseline laboratory values and vital signs.

Inclusion Criteria:

• Completed 3 months of dosing and Month 3 procedures in study M01-398
• Otherwise in good health
• Month 3 (M01-398) ultrasound reveals no significant gynecologic disorder

Exclusion Criteria:

• Any abnormal lab or procedure result the study-doctor considers important
• Anticipated need for excluded hormonal therapy or unapproved narcotics