Obesity is recognized as a risk factor of life-style related diseases. Dietary fat intake is higher than recommended in most western countries and is associated with the increased prevalence of those diseases. Recently some investigators have reported that catechins contained in green tea affected fat metabolism. The aim of this study was to investigate the influence of catechins intake on body fat reduction in humans. This study was carried out for 2 weeks of run-in period, l2 weeks of test period and l2 weeks of wash out period in a double blind study. Male subjects (average BMI 26.5 kg/m2, average age 42.1y) and postinenopausal female subjects (average BMI 25.9 kg/m2, average 54.8y) ingested a beverage containing 588mg (n=39, catechin group) or 126mg (n=41, control group) catechins a day during the test period. Body indices, abdominal fat area by CT scan and blood parameters were measured. Body fat parameters in the catechin group were significantly lower at the end of the test period than those in the control group. Furthermore, intake of catechins tended to reduce abdominal fat area in male subjects and tended to reduce subcutaneous fat area in female subjects. There were no significant differences between the groups in blood parameters. These results showed that consecutive intake of catechins reduces body fat, especially abdominal fat, possibly through activating fat metabolism in humans. Catechins may be useful in the prevention and reduction of obesity.