The prognosis, and clinical findings related to prognosis, were examined in a consecutive series of 190 patients under 76 years of age (mean 64 years) with congestive heart failure (CHF). The aetiology of CHF was ischaemic heart disease in 66%, hypertension in 11% and cardiomyopathy in 23%. The 2-year mortality was 32%. Median left ventricular ejection fraction (LVEF) was 0·30, range 0·06 to 0·74. Eight per cent were in New York Heart Association (NYHA) class I, 46% in II, 44% in III and 2% in IV. Multivariate analysis, excluding exercise test variables, revealed seven variables with independent, significant prognostic information, (hazard ratios for death in brackets): In (natural logarithm) (LVEF) (3·19), NYHA class III+IV (2·72), plasma urea>7·6 mmol. 1−1 (2·22), serum creatinine >121 μmol. 1−1 (2·05), serum sodium 65 years (1·86). Multivariate analysis, including exercise testing, showed the following variables to contain independent, significant prognostic information: increase in heart rate during maximal exercise ≤35 min−1 (3·5), In(LVEF) (3·7), serum creatinine >121 μmol. 1−1 (2·9), maximal exercise time ≤4 min (2·3), serum sodium 137 mmol. 1−1 (2·5), ischaemic heart disease (2·0) and plasma urea >7·6 mmol. 1−1 (19). In conclusion, patients with CHF have a high risk of death despite intensive medical treatment. LVEF is a strong predictor of mortality. Both NYHA class and exercise variables have strong independent prognostic information as regards mortality in combination with LVEF, but are mutually exclusive.