In the new world-wide criteria for metabolic syndrome (MetS) by the International Diabetes Federation (IDF) in 2006, the Japanese is the only ethnicity in which the recommended waist circumference (WC) cutoff value is higher in women (>or=90cm) than in men (>or=85cm), and its validity appears to be controversial. We investigated the optimal cutoff points for the diagnosis of central obesity in Japanese men and women, using the receiver operating characteristic (ROC) curve analysis for both of WC and visceral fat area (VFA) in 1870 middle-aged Japanese. VFA was superior to WC and Body mass index (BMI) for discriminating the subjects with two or more nonadipose components of MetS. The optimal cutoff points of VFA and WC were 132.6cm(2) and 89.8cm for men and 91.5cm(2) and 82.3cm for women. The stratifications of MetS components more than 1.0 in average occurred more steeply by the accumulation of VFA in women than in men. In conclusion, setting the cutoff points of WC and VFA lower values in women than in men for the definition of central obesity is needed to identify the subjects with MetS in Japanese, as in other Asian populations.