1. Serum total cholesterol (TCH), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein (LDL-C), atherosclerotic index (AI) and apolipoprotein (apo A-I, A-II, B, C-II, C-III and E) levels were investigated in patients with ischemic heart disease before and after medication of trapidil. 2. Twenty-one patients were orally given 100 mg of trapidil, three times daily (300 mg/day). After 8 weeks' administration, serum HDL-C level increased (P < 0.01) and AI decreased (P < 0.02) significantly, whereas TCH, TG and LDL-C levels tended to decrease but not significantly. 3. Among the parameters of apolipoproteins, apo A-I, a main protein of HDL-C, was significantly increased (P < 0.05) by trapidil. 4. These results indicate that trapidil has a beneficial effect on the coronary risk profile as reflected by lipid measurements.