Pantethine in a dosage of 600 mg for the first 3 months, and in a dosage of 1200 mg for the second 6 months was given to 16 diabetics in whom plasma beta-thromboglobulin was raised (greater than 50 ng/ml). Plasma beta-TG levels decreased significantly with pantethine treatment for 9 months. Plasma triglyceride, total cholesterol, apo E and apo CII levels decreased significantly after 9 months. Plasma LDL-C and atherogenic index (LDL-C/HDL-C ratio or apo B/apo AI ratio) tended to decrease with treatment. It is concluded that administration of pantethine may be beneficial in the prevention of diabetic angiopathy because of its lowering effect on plasma beta-TG, lipids and apolipoproteins.