Objective:We performed this meta-analysis to assess the association between metabolic syndrome (MetS) and benign prostatic hyperplasia (BPH). Method:We conducted extensive searches on the PubMed, Science and Cochrane Library to identify all articles. Outcomes including annual prostate growth rate, prostate volume (PV), International Prostate Symptom Score (IPSS), IPSS sub-scores (voiding and storage), prostate- specific antigen (PSA), maximum urine flow rate (Qmax), post-void residual urine volume (PVR) and quality of life (QoL) were assessed. Results:21 studies with 15,317 patients were included. Patients with MetS had higher annual prostate growth rate [weighted mean difference (WMD) = 0.79;p < .001], larger PV (WMD = 2.62;p < .001), lower Qmax (WMD = -0.48;p = .001) and more PVR (WMD = 8.28;p < .001). However, no significant differences were found between two groups in IPSS (WMD = 0.20;p = .37), IPSS-voiding (WMD = -0.05;p = .78), IPSS-storage (WMD = -0.22;p = .26), PSA (WMD = 0.04;p = .43), and QoL (WMD = -0.01;p = .70). Conclusions:The study suggested that MetS may be one of the risk factors for the clinical progress of BPH. However, further study is warranted to support these results.