The effects of glucose, sucrose, and fructose ingestion on the serum triglyceride responses to meals containing 40 g fat were studied in 21 normolipidemic, nonobese medical students (9 men, 12 women). Mean postprandial lipemia was not significantly lower after meals containing 50 g glucose and 40 g fat than after meals containing 40 g fat alone (2.11 vs 2.42 mmol.L-1.7 h-1, p greater than 0.45) despite a substantial increase in plasma insulin concentrations after the glucose-containing meal. Ingestion of 50 g fructose and 40 g fat (4.23 mmol.L-1.7 h-1, p less than 0.0001) and 100 g sucrose and 40 g fat (3.77 mmol.L-1.7 h-1, p less than 0.001) resulted in significantly greater lipemia than did the ingestion of fat alone. These findings suggest that the ingestion of insulinogenic carbohydrates does not reduce postprandial lipemia in normolipidemic subjects and that the ingestion of fructose and fructose-containing carbohydrates may augment the postprandial lipemia induced by a fat-containing meal.