The effect of 1-(m-trifluoromethylphenyl)-2-(beta-benzoyloxyethyl)-amino- propane hydrochloride (780 SE) on serum lipids, blood glucose and liver weight was studied in 4 experimental models, and compared with that of clofibrate and tiadenol. When rats were given a daily oral dose of 25 mg/kg or 50 mg/kg of 780 SE for 5 days a marked reduction of serum triglycerides and liver weight was observed. The decreases were more pronounced than those in rats treated with 50 mg/kg or 100 mg/kg of clofibrate or tiadenol. On the other hand, a reduction of serum cholesterol was only observed in the groups given clofibrate and tiadenol. These differences could be explained on the basis of the mechanism of action of the different drugs. Only 780 SE induced a decrease in blood sugar level, a reduction of plasma insulin concentration and restored the insulin sensitivity to a normal value in obese animals. There was a significant decrease in liver weight of 780 SE treated rats, whereas clofibrate and tiadenol cause hepatomegaly.