The long-term effect of a low-fat diet and physical training was investigated in 36 men (mean age 51 +/- 6 years) with coronary heart disease (one-vessel disease, n = 11; two vessel-disease: n = 18; three-vessel disease: n = 7). 18 patients (interventionist, group 1) undertook physical training within a coronary sport group (1 h twice weekly) and daily bicycle ergometry (30 min). They were held to a low-fat diet. In the remaining 18 patients (control, group 2), physical training and low-fat diet depended on own initiative after receiving advice. Over an observation period of 6 years total cholesterol concentration in the 17 patients of group 1 decreased significantly (243 +/- 33 vs. 219 +/- 28 mg/dl; P < 0.02). Physical performance in 12 patients (group 1) increased from 169 +/- 40 to 202 +/- 42 W in (P < 0.01). In contrast, total cholesterol increased slightly in group 2 (n = 16) from 245 +/- 31 at the beginning to 247 +/- 39 mg/dl (no significant change) at the end of the 6 years. Physical performance (n = 12) decreased slightly from 165 +/- 45 to 146 +/- 52 W (not significant). The difference between the two groups was significant after 6 years (P < 0.02 and P < 0.007, respectively). There seemed to be a tendency for progression of the coronary heart disease to be slower in the interventionist than the control group.