BACKGROUND: InBody 4.0, a bioelectrical impedance analyser (BIA) has an automatic function of printing out the measurement data of visceral fat area. The purpose of this study was to assess the usefulness of the visceral obesity measured by the InBody 4.0 and the waist circumference METHODS: A total of 124 participants who visited an obesity clinic in a university hospital were measured their waist circumference, height, weight and the visceral fat area by the InBody 4.0 and CT scan. The mean difference and agreement between the two visceral fat areas by the two methods had been analyzed according to sex, age and BMI groups. The accuracy of the visceral obesity by the BIA and the waist circumference was respectively compared with the visceral obesity by the CT scan. RESULTS: There was no significant difference between visceral fat area measured by the CT and the BIA in women participants under 46 years of age and below BMI 30. When comparing visceral fat area obtained from the CT with those obtained from the BIA, the 95% confidence interval for the limit agreement was higher in male subjects than in females. The waist circumference was the more sensitive method to diagnose visceral obesity than the BIA (91.80% vs. 77.94%), but the BIA method showed a higher specificity than the waist circumference (76.79% vs 52.38%). CONCLUSION: Waist circumference turned out to be more useful than the BIA as a screening tool for visceral obesity. In the group of males, BMI of over 30, or the age over 46 years, it is recommended that the CT rather than the BIA for measurement of visceral fat area be utiliged.