This study was undertaken to evaluate the combined effects of sucrose feeding and exercise training on serum insulin, triglycerides, as well as cholesterol and its distribution into lipoproteins of female Wistar rats. The animals were fed ad libitum either laboratory chow alone, or chow and a 32% aqueous sucrose solution. Half of each dietary group was submitted to an exercise-training program. Both sucrose feeding and exercise training elicited greater energy intake. Sucrose feeding produced a marked elevation in triglyceridemia that was prevented by exercise training. Insulin levels paralleled those of triglycerides. The sucrose-fed animals had higher total cholesterol levels than the animals given chow. Although exercise training did not affect total cholesterol in the chow-fed animals, it partly prevented the sucrose-induced elevation in total cholesterol. Cholesterol in the lipoproteins of lower densities was increased significantly with sucrose feeding, and exercise training totally prevented this augmentation. The amount of cholesterol carried by high-density lipoprotein (HDL) was not affected by exercise training in the chow-fed animals. In contrast, sucrose feeding increased HDL-cholesterol in sedentary animals, whereas exercise training partly prevented this increase. The HDL/total cholesterol ratio was similar in all groups. Changes in insulin concentration underline the importance of this hormone in the regulation of blood lipid levels.