Congestive heart failure in patients with prosthetic valves is a complex syndrome which poses difficult clinical and therapeutical problems. In order to identify etiologic factors, pathophysiologic substrates, clinical pictures and natural history we retrospectively evaluated 124 consecutive patients (mean age 61 +/- 11 years) with prosthetic valves, hospitalized during the 1984-1990 period because of congestive heart failure. The following main etiologies were identified: acute prosthetic valve failure (19%), chronic prosthetic failure (15%), preexisting left ventricular dysfunction (9%), newly acquired left ventricular dysfunction (8%), associated valve diseases (15%), chronic constrictive pericarditis (2%), multiple causes (31%). At a mean follow-up of 8.9 +/- 4.5 years, mortality was 8.8%/patients/year in the whole group, 3% in the subgroup with chronic prosthetic failure and 19% among the cases with preexisting left ventricular dysfunction. Among the patients who underwent reoperation because of prosthetic failure, the following were incremental risk factors: mechanical (vs biological) failing prosthetic valve, mitral prosthesis, emergency operations, mitral and or aortic insufficiency as the initial diagnosis. The preliminary knowledge of the possible etiologies and of the pathophysiologic substrates can help the physician while treating the single patient with heart failure after valve replacement. Many implications derived from this kind of patients are also useful in order to select surgical candidates among patients with valve disease.