Objective: To assess the effectiveness and safety of omega-3 fatty acid for patients with PCOS. Methods: In this meta-analysis, data from randomized controlled trials were obtained to assess the effects of omega-3 fatty acid versus placebo or western medicine in women with PCOS. The study's registration number is CRD42017065859. The primary outcomes included the change of homeostatic model assessment (HOMA) of insulin resistance, total cholesterol (TC), triglyceride (TG) and adiponectin. Result: Nine trials involving 591 patients were included....