Objective: Metabolic Syndrome (MetS) is a multisystem disorder. The presence of the MetS is an important risk factor for cardiovascular disease and diabetes. Metabolic abnormalities have consistently been identified as a part of mental illness. Leptin is a hormone found increased in obese individuals. We aimed to evaluate correlation between MetS and serum leptin levels in bipolar patients. Methods: The study included 60 bipolar I outpatients who applied to the Gaziantep University Medical Faculty, Mood Disorders Unit of Psychiatry Department diagnosed according to the DSM IV. They were assessed cross-sectionally for MetS according to the National Cholesterol Educational Program criteria (NCEP ATP III). High-density lipoprotein (HDL)-cholesterol, glucose and triglyceride levels were measured by biochemical autoanalyzer via enzymatic-calorimetric method. Leptin levels were determined using enzyme-linked immunosorbent assay in S.U. Meram Faculty of Medicine Department of Biochemistry. Blood pressure and waist circumference at the level of the umbilicus were measured. Results: Of the patients, 36.7% were dignosed with MetS, a proportion higher than normal populations and similar to previous studies in bipolar patients. There was no significant correlation between MetS and serum leptin levels. The only significant difference between MetS NCEP ATP III criteria and serum leptin levels is abdominal obesity. Conclusions: This is the first study in bipolar patients investigating metabolic syndrome (MetS) and correlation with serum leptin levels. There is correlation between higher leptin levels and abdominal obesity but no correlation between MetS and leptin levels.