Metabolic syndrome is associated with an increased risk of diabetes and cardiovascular disease. Although some data suggest that the prevalence of metabolic syndrome is higher in patients undergoing peritoneal dialysis (PD), the factors related to this increased risk are not well elucidated. We therefore examined whether peripheral white blood cell (WBC) count is correlated with the risk of metabolic syndrome in nondiabetic PD patients. We enrolled 104 nondiabetic PD patients without current infections or chronic inflammatory diseases. Complete blood cell count, anthropometry, blood pressure, fasting glucose, insulin, and lipid profiles were measured. Metabolic syndrome was defined in accordance with the National Cholesterol Education Program (Adult Treatment Panel III) criteria. Metabolic syndrome was present in 49 patients (47.1%). Patients with metabolic syndrome had a higher WBC count and high-sensitivity C-reactive protein level. As the number of metabolic syndrome components increased, WBC count increased significantly. White blood cell count was significantly positively correlated with body mass index, insulin, homeostasis model assessment of insulin resistance, and triglyceride and negatively correlated with high-density lipoprotein cholesterol. The risk of metabolic syndrome increased significantly with a higher WBC count, resulting in an adjusted odds ratio of 1.65 (per 103/μL increase, P = .002). These findings demonstrate that metabolic syndrome is prevalent among nondiabetic PD patients and that WBC count is strongly associated with metabolic syndrome and its components.