We examined 82 patients 10 years after saphenous-vein aortocoronary bypass surgery to determine their angiographic status and to relate those findings to the risk factors for coronary-artery disease. Of 132 grafts shown to be patent 1 year after surgery, only 50 were unaffected at 10 years. The remainder were narrowed (43) or occluded (39). Disease progression in coronary arteries without grafts was also frequent, both in vessels that were normal (15 of 32) and in those with minor stenosis (25 of 53). New lesions did not develop in 15 patients, whereas they did in 67--in the grafts, the native vessels, or both. There was no significant difference between the two groups in the incidence of hypertension, diabetes, or smoking, whereas plasma levels of very-low-density lipoproteins (VLDLs) and low-density lipoproteins (LDLs) were higher, and high-density lipoprotein (HDL) levels were lower in those with new disease than in those without. Univariate analysis showed that plasma cholesterol and triglyceride levels were significantly higher at the time of surgery and at the 10-year examination in those with new lesions. Multivariate analysis indicated that among the lipoprotein indexes, levels of HDL cholesterol and plasma LDL apoprotein B best distinguished the two groups. The findings indicate that atherosclerosis in these patients was a progressive disease, frequently affecting both the grafts and the native vessels, and that the course of such disease may be related to the plasma lipoprotein levels.