The influence of pre-operative serum lipid levels on late clinical outcome after coronary artery bypass surgery was analysed in 83 patients undergoing coronary bypass surgery for stable angina pectoris. The mean follow-up period for surviving patients was 105 +/- 33 months (range 65-133). Twenty-two patients (27%) had died during follow-up, of whom 14 had sustained a fatal myocardial infarction and four had succumbed to other cardiovascular causes. Thirty-one patients sustained 35 cardiac events, defined as either fatal or non-fatal myocardial infarction, or reoperation, or PTCA during the follow-up period. With univariate analysis, pre-operative serum levels of total cholesterol and triglycerides were significantly related to cardiac events, P < 0.05 and P < 0.05, respectively. In a Cox proportional analysis, cardiac mortality and total mortality were related to serum triglycerides and HDL cholesterol (P < 0.05 and P < 0.01 respectively). Eighty-five percent of the patients with triglycerides < 2.0 mM.l-1 survived for 10 years, while only 48% of patients with triglycerides > 2.0 mM.l-1 remained alive for that period. Figures were similar for subjects with HDL cholesterol > 1.0 mM.l-1 or HDL cholesterol < 1.0 mM.l-1, at 89 and 38%, respectively. Only 28% of the patients with the combination triglycerides > 2.0 mM.l-1 and HDL cholesterol < 1.0 mM.l-1 were alive 10 years after surgery. These data suggest that dyslipidaemia, especially the combination of high serum triglycerides and low HDL cholesterol, is an important factor influencing long-term clinical outcome after coronary bypass surgery.