An abnormally high mortality from atherosclerotic cardiovascular (CV) accidents has long been reported in patients on maintenance hemodialysis (HD). However, incidence of such complications had not been so far evaluated in chronic renal failure (CRF) patients not yet on dialysis. In a cohort study bearing on 232 predialysis CRF patients, followed as out-patients at Necker hospital, incidence of first myocardial infarction (MI) was three times higher than in the French general population in every age group and in both genders, with a mean (+/- SEM) age at onset of MI of 62.9 +/- 1.2 years. In a retrospective cooperative study involving 748 patients treated in 9 hemodialysis centers in the Ile-de-France area, incidence of first MI episodes did not differ before and after start of HD therapy and was similar to that observed in the cohort study. Mean age of patients at first MI, before and after start of HD, was respectively 62.4 +/- 1.6 and 63.7 +/- 1.5 years, a not significant difference. In conclusion, two epidemiologic studies confirm the existence of accelerated atherosclerosis in CRF patients, the incidence of MI being 3 times higher in uremic patients than in the general population in every age group and in both genders. The fact that incidence of first MI episodes and age at onset was similar in predialysis and in dialyzed patients suggests that the uremic state per se is a main determinant of such accelerated atherosclerosis. It results that therapeutic measures aimed at preventing development of atherosclerosis should be initiated from the early stage of CRF, long before start of renal replacement therapy.