In an attempt to study the influence of heart transplantation on the natural history of patients with severe congestive heart failure, we have reviewed our experience with 240 consecutive patients who were New York Heart Association class IV or III/IV, who had left ventricular ejection fraction less than 35%, who were younger than 65 years of age, and who were assessed for heart transplantation in our hospital since May 1986. Mean age was 47 +/- 12 years. Left ventricular ejection fraction was 20% +/- 6%. Eighty-seven percent were male. New York Heart Association class was IV in 88% and III/IV in 12%. The cause was ischemic heart disease in 35% of patients, valvular heart disease in 13% of patients, and primary dilated cardiomyopathy in 52% of patients. At initial assessment, heart transplantation was considered to be not indicated in 30% of patients, indicated in 51% of patients, and contraindicated in 19% of patients. During a follow-up of 13 +/- 13 months (2 to 64 months), 110 patients underwent transplantation (46%). Posttransplantation actuarial probability of survival was 70% at 3 years. Three-year probability of survival free from transplantation was significantly lower for patients older than 55 years of age (p < 0.05), for those with left ventricular ejection fraction less than 20% (p < 0.05), ischemic causes (p < 0.05), New York Heart Association class IV (p < 0.001), and indication/contraindication for transplantation (p < 0.001); no difference was noted for gender.(ABSTRACT TRUNCATED AT 250 WORDS)