Multivariate analysis was used to analyze the morphometric data of endomyocardial biopsies (area, perimeter and minor diameter) of myocardial cells obtained at light microscopy by a computerized approach with 16 clinical parameters and prognosis in 52 patients with idiopathic dilated cardiomyopathy. The best morphometric parameter was "area" (R2 = 0.47). A positive correlation was found with age (p less than 0.02), interval between first symptoms and diagnosis (p less than 0.02), left ventricular end-diastolic volume (p less than 0.02), cardiac index (p less than 0.05) and echocardiographic end-diastolic diameter (p less than 0.1). A negative correlation was found with prognosis (p less than 0.02), ejection fraction (p less than 0.02), shortening fraction (p less than 0.05), echocardiographic end-systolic diameter (p less than 0.06) and mitral regurgitation presence (p less than 0.1). The parameters that provided no correlation were New York Heart Association class, left ventricular end-diastolic pressure, right atrial pressure, cardiothoracic ratio, presence or absence of heart failure, fever or alcohol intake. These findings suggest that endomyocardial biopsy may provide prognostic information and confirm clinical diagnosis.