Three-week old female mice were ovariectomized. From weaning at 4 weeks they were fed either a control or a high fat diet. When 32 weeks old, the ovariectomized mice weighed more than the sham-operated ones, whichever diet they were fed. Food intake decreased 140 days after castration. Ovariectomized mice fed the control diet showed fat cell hypertrophy at three sites and hyperplasia of the perirenal tissue. In mice fed the fat-rich diet, ovariectomy only caused further hypertrophy in the subcutaneous and perirenal adipose tissue.