Hypercholesterolemia, induced by feeding rats a diet of cholesterol and cholic acid, can be markedly accentuated by diabetes, resulting in serum cholesterol levels greater than 1000 mg/dl and extensive accumulate of cholesterol in the liver. To examine the cellular events of hepatic cholesterol accumulation in cholesterol-fed diabetic rats, we used a fixative containing digitonin and water-soluble embedment to preserve native lipid structures.Sprague Dawley male rats were made diabetic by intravenous injection of streptozotocin (45 mg/kg body weight) and fed a powdered diet containing 2% cholesterol, 10% lard and 1% cholic acid (CLC) for 3 wk. Non-diabetic rats were also fed CLC diet. Cholesterol, glucose and insulin levels were monitored for both groups. Livers were fixed by perfusion with 3% glutaraldehyde (30°C) and 0.2% digitonin in cacodylate buffer (1 hr), then by 1% OsO4 in buffer for 2 hr. Staining was in 2% uranyl acetate and embedding in water soluble urea glutaraldehyde. Thin sections were stained with lead citrate and viewed in a Zeiss EM-9S.