Male Sprague-Dawley rats were fed either a low-chromium (60 to 100 micrograms per kg of diet) or chromium-supplemented (5 mg per kg of diet), high-sucrose, high-cholesterol diet from weaning until age 18 months. Rats that were pair- and meal-fed the low-chromium diet had higher one-hour postprandial plasma glucose concentrations than their supplemented partners at ages 4 and 8 months (P less than 0.05), but not at age 12 months. One-hour postgavage (250 mg glucose/100 g body wt) glucose concentrations did not differ between dietary groups at 12 months. Plasma cholesterol concentrations increased up to age 12 months, but neither they nor postprandial triglyceride concentrations differed significantly between dietary groups. Ad libitum feeding of the low-chromium and chromium-supplemented diets was initiated at age 14 months in order to determine whether there were differences due to dietary chromium content which might not be manifest on the pair-feeding regimen. Animals of both dietary groups had significant weight gain by age 16 months, but their one-hour postgavage plasma glucose concentrations did not differ significantly. Plasma cholesterol concentrations increased significantly following institution of ad libitum feedings, but neither they nor lipoprotein cholesterol or triglyceride distributions differed significantly between dietary groups. Experimental conditions, methods, and results from this study and previous studies are compared and critically examined. We suggest that other factors in addition to dietary chromium content may contribute to the differences in glucose tolerance and plasma cholesterol concentrations described in such studies and that there is a need for improved documentation of glucose intolerance and tissue chromium concentrations in this animal model.