The purpose of this investigational study is to determine if a study medication is safe and effective in reducing the symptoms associated with endometriosis; if the study medication reduces the need for pain medication for endometriosis symptoms; and if the study medication improves a participant's ability to carry out daily activities. Qualified participants will receive no cost treatment, which may include study-related examinations, diagnostic procedures including a Pap smear, laboratory testing, and a mammogram (aged 40-45). Qualified participants will also receive study medication at no cost. As a participant, the study volunteer may also experience the satisfaction of knowing she is helping the advancement of women's health care.

Inclusion Criteria:

• Surgical diagnosis of endometriosis within 5 years
• Not pregnant and not lactating
• Willing to use non-hormonal contraception, history of regular menstrual cycles

Exclusion Criteria:

• Hysterectomy, surgical treatment for endometriosis within 3 months
• Certain medications for the treatment of endometriosis
• Previous history of a malignancy
• Abnormalities on physical or gyn exams and abnormal lab tests