In order to determine the effect of milk products on serum cholesterol, triglycerides, and diet, 54 volunteers were studied for varying periods with dietary supplementation of nonpasteurized yogurt, pasteurized yogurt and 2% butterfat milk. Serum cholesterol was significantly reduced by 5 to 10% after 1 week of supplementation with either nonpasteurized or pasteurized yogurt; 2% butterfat milk reduced serum cholesterol to a smaller and less significant effect. Serum triglycerides were unaffected by the diet and dietary intake studies confirmed that intake of other nutrients remained relatively stable throughout the study. Supplementation of diet with yogurt may have a helpful hypocholesterolemic effect.