40 patients with primary hypercholesterolemia were included in a randomized cross-over trial comparing effects and tolerance of bezafibrate (Cedur) (200 mg t.i.d.) and colestyramine (4 g t.i.d.). Gastrointestinal side-effects led to the discontinuation of colestyramine in 11 patients. No adverse events were observed with bezafibrate. Both drugs had similar effects on total and low density lipoprotein cholesterol (bezafibrate: -15% and -12%, respectively; colestyramine: -10% and -11%, respectively). While the high density lipoprotein-increasing effect of bezafibrate was more marked (+20% vs. +14%), triglycerides and very low density lipoprotein cholesterol were lowered by bezafibrate (-22% and -27%, respectively) and tended to increase with colestyramine (+11% and +10%, respectively). In the light of results of a multicenter primary prevention trial bezafibrate also should have a protective effect on coronary heart disease. This, however, has to be proven in longterm prospective trials.