Subjects with documented uterine fibroids, screening UFS-QOL severity score of at least 40, and meeting other eligibility criteria will be enrolled in the study. Following screening and a pre-treatment endometrial biopsy, subjects will be assessed monthly for the four (4) month double-blinded treatment phase. The study duration is approximately six months, comprised of a one-month screening period, 4 month treatment period and one month follow-up period. Subjects' blood will be drawn in a fasting state to obtain the pre-dose trough (PK) levels of study drug at each study drug dosing/dispensation visit to determine the potential for drug accumulation.