Cardiovascular impairment is considered a major cause of reduced tolerance to haemodialysis in elderly patients and is thought to require a soft dialysis strategy in these patients. To verify these observations we compared dialysis strategy and tolerance of patients over 65 years old to those of patients under 45 years, since atherosclerotic/involutional changes of vasculature should be quite different in these groups. Seventy-seven elderly and 57 young patients (age 72 +/- 5 and 35 +/- 6 years respectively, mean and SD) were selected from a population of 292 patients undergoing regular dialysis treatment exclusively on the basis of the age criterion. Cardiovascular impairment was found to be greater (as expected) in older than in younger patients, as documented by a larger proportion of diabetic patients (19% vs 3%), a greater incidence of cardiovascular manifestations both before the beginning of dialysis (27% vs 10% of patients affected) and after the beginning of dialysis (35% vs 16%), a greater incidence of ECG abnormalities (78% vs 56%), a longer exposure to hypertension (9.2 vs 3.5 years), and a greater utilisation of digitalis (36% vs 5%) and nitrates (19% vs 2%). Dialysis strategy in elderly patients differed from that in young patients only for a moderately lower blood flow rate (243 vs 279, 244 vs 279, ml/min, males and females respectively). Dialysis sessions were shorter in older than in younger males (11.8 vs 12.4 h/week). The incidence of intradialytic hypotension did not differ significantly between the two groups (44% vs 32%), although the elderly showed a greater pre-to-post-dialysis systolic arterial pressure reduction (21 vs 15 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)