Objective To explore the relationship between metabolic syndrome (MS) and prostate volume. Methods One thousand and ninety-eight males aged 36-90 years were divided into two groups according to the definition of MS by CDS in 2004 : MS group and control group. The blood pressure, body weight and height were measured, and the body mass index (BMI) was calculated. Biochemical assays including fasting plasma glucose, total cholesterol, triglycerides, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and prostate specific antigen (PSA) were performed. Prostate volume was measured by abdominal ultrasound. Results (1) The BMI, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, serum triglyceride, total cholesterol, prostate volume and PSA level were higher, while HDL-C level was lower in MS group than in control group (all P<0.05). (2)Compared with control group, the prostate volume was enlarged in MS group [(37.8±21.3)ml vs. (31.0±11.1)ml, P<0.01]. (3)The prostate volume was positively correlated with PSA level (r= 0. 350, P< 0. 01), age (r = 0. 429, P<0.01), BMI (r=0.145,P<0.01) and systolic blood pressure (r=0.133, P<0.05), and was negatively correlated with diastolic blood pressure (r= -0. 193,P<0. 01). ConclusionsMetabolic syndrome is related to the enlargement of prostate volume.