The objectives of this study are to estimate the efficacy and safety of the daily administration for 6 months of 5 mg versus 10 mg. A 6 month follow-up of subjects is carried out to estimate how the effects of mifepristone are kept in time.

The hypothesis of this study is that both mifepristone doses reduce the volume of the myoma up to 50% in six months treatment.

Women, in fertile age or premenopausal status, presenting symptomatic myomaswere randomly assigned to receive 5 or 10 mg of mifepristone for six months.

The decreasing in the prevalence of symptoms attributable to myomas is an important goal to achieve under both treatments. Another goal is to maintain for more than 6 months the benefits of the treatment with mifepristone.

Inclusion Criteria:

• Symptomatic uterine fibroids
• Reproductive age or premenopausal
• Accepting the use of non hormonal contraception
• Conformity in keeping a monthly log of all episodes of vaginal bleeding during the treatment as well as the side effects of mifepristone
• Agreeing to have ultrasound examinations in every follow-up or evaluation visit
• Agreeing in two endometrial biopsies: one before starting treatment and another in the following 10 days after treatment termination

Exclusion Criteria:

• Pregnancy or desire to become pregnant
• Breastfeeding
• Hormonal contraception or any hormonal therapy received in the last three months
• Signs or symptoms of pelvic inflammatory disease
• Adnexal masses
• Abnormal or unexplained vaginal bleeding
• Suspected or diagnosed malignant neoplastic disease
• Signs or symptoms of mental illness
• Adrenal disease
• Sickle cell anemia
• Hepatic disease
• Renal disease
• Coagulopathy
• Any other severe or important disease
• Any contraindication to receiving antiprogestins