The effects of physical exercise and dietary fats on blood pressure and lipid metabolism were studied using spontaneously hypertensive rats (SHR). The animals, aged 5 weeks, were fed two semipurified, fat-laden diets containing 1) 10% lard (L-diet) and 2) 10% safflower oil (S-diet) followed by a 15-week exercise program (from 11 weeks of age). Body weight, blood pressure and serum lipid levels were measured. The average body weight was greater than that of nonexercised rats. Blood pressure in the exercised groups for both diets was significantly lower than that in the non-exercised groups. Serum lipid levels, including total lipids, total cholesterol, triglyceride and free fatty acid of exercised L-diet rats were clearly lower than in the non-exercised L-diet rats. These parameters for the exercised S-diet rats were also lower, but were not significantly different, except triglyceride. The serum triglyceride level in the exercised rats was significantly lower than in the non-exercised rats for both diets, w ereas HDL-C in the exercised rats was higher for both diets. Physical exercise was thus shown to be effective for lowering hypertension and suppressing hyperlipemia due to dietary fats.