To assess the hypolipemic and antiatherosclerotic activity of diprophyllinyl-4-benzyloxybenzoate guinea-pigs were kept on a high-lipid diet alone or with the tested compound for 21 days, and rabbits--for 3 months. It was found that diprophyllinyl-4-benzyloxybenzoate displays a distinct hypolipemic activity, particularly with respect to cholesterol, both in guinea-pigs and rabbits. It also depresses the cholesterol and the trigliceride content in liver homogenates and shows a tendency to normalize the low-density-lipoprotein fraction in guinea-pigs, as well as cholesterol of the high-density lipoprotein fraction, and malon dialdehyde in rabbits. The area of intima covered with atheromatous plaques was smaller in rabbits receiving the high-lipid diet with diprophyllinyl-4-benzyloxybenzoate than in those receiving that diet alone.