The Paris Prospective Study is a long term investigation of the incidence of coronary heart disease in a large population of working men. The first follow-up examination involved 7,038 men, aged 43-54 years, and free from cardiovascular disease. A 0-2 h 75 g oral glucose tolerance test with measurement of plasma insulin and glucose levels was performed, and the major coronary heart disease risk factors were determined. Subjects with impaired glucose tolerance or diabetes at baseline (n = 943) were selected from the total population for a separate analysis of coronary heart disease mortality risk factors. After a mean follow-up of 11 years, 26 of these 943 subjects with abnormal glucose tolerance had died from coronary heart disease. In multivariate regression analysis using the Cox model, triglyceride plasma level was the only factor positively and significantly associated with death from coronary heart disease (p less than 0.006). After a mean follow-up of 15 years, 37 of the 943 had died from coronary heart disease. Significant multivariate predictors of coronary heart disease death with the Cox model were triglyceride plasma level (p less than 0.03), systolic blood pressure (p less than 0.03), and number of cigarettes per day (p less than 0.05). This epidemiological evidence of the consistency of hypertriglyceridaemia as an important predictor of CHD mortality in subjects with impaired glucose tolerance or diabetes suggests a possible role of dyslipidaemia in the excessive occurrence of atherosclerotic vascular disease in this category of subjects. It remains speculative how this dyslipidaemia can be related to arterial damage, whether by itself or as part of the insulin resistance syndrome.