Polycystic ovarian syndrome (PCOS) is a metabolic and hormonal condition affecting women of a reproductive age. It causes an abnormal menstrual cycle, anovulation, infertility, acne, hirsutism, obesity, hyperlipidemia, and cardiovascular disorders. Because resveratrol decreases testosterone levels, it may be of value in treating PCOS. We aimed to evaluate the efficacy of resveratrol in treating women with PCOS. We searched for randomized clinical trials (RCTs) in PubMed, Cochrane CENTRAL, Scopus and Web of Science. With 95% confidence intervals, the data was retrieved and analyzed as a mean difference (MD) or a standardized mean difference (SMD). Four RCTs with 218 women were included in the analysis. Resveratrol significantly reduced testosterone (SMD = -0.40; 95% CI [-0.71, -0.10], P = 0.009), luteinizing hormone (LH) (SMD = -0.32; 95% CI [-0.62, 0.01], P = 0.04), and dehydroepiandrosterone sulfate (DHEAS) (MD = -0.85; 95% CI [-1.25, -0.45], P < 0.0001) compared with the placebo. Resveratrol is effective in treating women with PCOS due to reducing the levels of testosterone, LH, and DHEAS. In combination with other treatments, especially for hyperlipidemia, resveratrol is beneficial for women diagnosed with PCOS.