This article reports a study in which the percent of fat estimated from bioelectrical impedance-total body water measurement and skinfold-body density method in Japanese women were compared. The bioelectrical impedance measurement provides a new approach to assessment of human body composition that is based on the principle that the electrical conductivity of lean body mass, which includes the protein matrix of adipose tissue, contains virtually all the water and conducting electrolytes in the body, is far greater in lean body mass than fat mass. In a sample of 60 women varying widely in body weight (42.20 to 69.19kg), and adiposity (21.4 to 52.9 % body fat by bioelectrical impedance-total body water measurement and 16.2 to 46.2 % body fat by skinfold thickness method), the correlation between the percent of fat derived from skinfold thickness method and the percent of fat predicted from bioelectrical impedance-total body water measurement by use of a previously developed regression equation was extremely strong (r=0.842, p<0.001). The percent of fat predicted from bioelectrical impedance-total body water measurement by use of prediction equation provided with the instrument also correlated with skinfold thickness at 14 sites (r=0.328 - 0.805) but overestimated the percent of fat compared with the percent of fat from skinfold thickness method. The significant, positive correlation between internal fat and the differences of the percent of fat by two methods was observed, but the external fat was not correlated significantly with those differences. Accordingly, this new method promises to provide a useful technique for the evaluation of the internal body fat, which are correlate well with metabolic abnormalities such as glucose intolerance, hyperinsulinemia, and hyperlipidemia.