To assess the effect of low-dose mifepristone on quality of life, pain, bleeding, and uterine size among women with symptomatic leiomyomata. Forty-two women with symptomatic uterine leiomyomata and uterine volume of 160 mL or more were randomized to mifepristone, 5 mg daily, or placebo for 26 weeks. Quality of life (Uterine Fibroid Symptoms Quality of Life Questionnaire and Medical Outcomes Study 36-Item Short Form survey) and uterine and leiomyoma size (ultrasonography) were assessed at baseline, and at 1 month, 3 months, and 6 months of treatment. Bleeding (daily logs and pictorial charts) and pain (McGill Pain Questionnaire) were assessed monthly. Endometrial pathology was assessed at baseline and 6 months. Forty-two women were randomized; 37 women completed all 6 months. Women randomized to mifepristone showed an improvement in leiomyoma-specific quality of life. Forty-one percent became amenorrheic, rates of anemia improved, and adjusted uterine size was reduced by 47%. Compared with the placebo group, improvements in these outcomes in the treatment group were significantly greater (P<.05 to .001). There were no significant differences in adverse effects between the groups. No endometrial hyperplasia was noted in any participant. Low-dose mifepristone improves leiomyoma-specific quality of life and reduces leiomyoma size among women with symptomatic leiomyomata. ClinicalTrials.gov www.clinicaltrials.gov NCT00133705 I.