This study was performed to evaluate the relationship between serum phosphate levels and cardiovascular risk factors and metabolic syndrome components in a cross-sectional survey. Plasma phosphate was measured by immunoturbidimetry in 46,798 subjects over 20 years of age with an estimated GFR>or=60 mL/(min 1.73 m(2)) who participated in a health-check survey at the Kangbuk Samsung Hospital in South Korea. The median plasma phosphate level was 3.49+/-0.44 mg/dL and the mean estimated GFR was 77.46+/-8.51 mL/(min 1.73 m(2)). We found that serum phosphate levels had a positive correlation with total cholesterol, HDL-C, lipoprotein a, apolipoprotein A1, calcium, and albumin. In addition, serum phosphate levels had a negative correlation with age, body mass index, uric acid, fasting glucose, insulin, HOMA-IR, HS-CRP, triglyceride levels, systolic blood pressure, diastolic blood pressure, and waist circumference (P<0.001). In conclusion, we found that a high phosphate level is correlated with cardiovascular disease while a lower phosphate level is correlated with metabolic syndrome. Serum phosphate levels that were too high or too low correlated with cardiovascular risk factors and elements of metabolic syndrome, respectively, showing that it may be important to maintain an appropriate level of phosphate for the prevention of cardiovascular events and metabolic syndrome.