Vitamin E in conventional therapeutic doses (400 mg/day) was given to 17 patients with hyperlipidemia on long-term treatment with diets enriched in polyunsaturated fatty acids and with clofibrate. The effect of this treatment on total serum cholesterol and on serum triglycerides was studied. To avoid influences of other factors (especially changes in dietary habits) the investigation was performed giving the patients tocopherol and placebo randomly, double blind and cross-over. No significant effect of vitamin E on total serum cholesterol or on serum triglycerides was seen.