Abstract: AIM: To evaluate the efficacy and safety of Mifepristone in treating patients with premenstrual syndrome(PMS). METHODS: 80 subjects diagnosed with PMS were participated in the study. The study was designed as randomized double blind placebo controlled trial. The experimental group was treated with Mifepristone for 3 months, while controlled with placebo. And a 3-month follow up for effectiveness and safety would be taken and experimental.RESULTS: The total effective rates of experimental and controlled were 92.5% and 45% respectively, and the total clinical effect rates of 3-month follow up were 90% and 37.5% respectively, comparisons of the two indices were significantly different(P<0.05). As for safety, there was no significant difference.CONCLUSION: Mifepristone can improve the PMS. And its effect is obvious, with more safety less side effects in treating PMS.

Key words: Premenstrual syndrome, Mifepristone, Double blinded randomized design