Background: The present study investigates the effect of Juzentaiho-to on normal weight increase in rats. Juzentaiho-to is a traditional Japanese ‘Kampo’ medicine and causes increased appetite in patients. Method: Ten male 4-week-old wistar rats were divided into two groups. The five rats of the J group were fed CE-2 including 1% Juzentaiho-to, and the five rats of the C group were fed CE-2. The animals weights were measured weeekly. Results: The J group had grown significantly heavier than the C group at 15 weeksold. Conclusions: Juzentaiho-to causes an increase in body weight in rats.