Endomyocardial biopsies showing histological evidence of "ordinary" hypertrophy or changes compatible with congestive cardiomyopathy (COCM) were obtained from 125 patients. Statistical analysis compared histological/morphometric data with clinical/haemodynamic findings such as ejection fraction, left ventricular end-diastolic pressure, and length of history. Patients were grouped either according to the histological description or the clinical diagnosis. Comparison of the morphological description with the final clinical diagnosis was also undertaken. Follow-up of the patients was between two and 66 months. The results of the statistical analyses showed no correlation between quantitative, morphological assessment and either clinical information, that is length of history and subsequent course, or the haemodynamic variables. In 86 per cent of cases a rough agreement between the morphological description and the clinical diagnosis was obtained, but no specific pattern permitting a morphological diagnosis of COCM was established. The findings suggest that pronounced topographic variation in biopsy material exists and that, therefore, the severity of COCM or its prognosis cannot be assessed from histological changes.