Serum lipid, lipoproteins, apolipoproteins and plasma insulin and glucose were studied in rhesus monkeys (Macaca mulatta) fed high sucrose diets (69%, w/w), with and without added cholesterol. When compared to basal diet, a high sucrose diet with no added cholesterol fed for 6 weeks increased serum total cholesterol and triglycerides by factors of 1.2 and 2.8, respectively. Cholesterol supplementation of sucrose diets increased the serum total cholesterol levels by a factor of 2.2 and decreased the serum triglycerides by 0.47. The serum cholesterol response to experimental diets was reflected predominantly in beta-lipoprotein and to a lesser extent in alpha-lipoprotein. Sucrose diets without cholesterol enriched the beta- and pre-beta-lipoproteins with triglycerides and protein at the expense of cholesterol. On the same diet, the protein content of alpha-lipoprotein increased at the expense of cholesterol and triglycerides. In contrast, dietary cholesterol decreased the triglyceride content and increased the cholesterol content of all the lipoprotein classes. Sucrose feeding seems to increase ApoB more than non-ApoB proteins. The proportion of ApoC-II relative to ApcoC-III increased in each animal on a sucrose diet; exogenous cholesterol further increased this trend. While sucrose diet decreased ApoA-I/ApoA-II ratios, cholesterol supplementation reversed this trend. Dietary sucrose increased the plasma glucose, insulin, and insulin-glucose ratios. The addition of cholesterol also tended to decrease plasma glucose and insulin levels. These observations indicate varied responses of serum lipoproteins and apoproteins to dietary sucrose with and without cholesterol supplementation.