Detailed comparisons were made of the individual interpretations by 7 cardiovascular pathologists, of histologic sections of endomyocardial biopsy specimens from 16 patients with the clinical diagnosis of dilated cardiomyopathy. Analysis of the data showed that interobserver variability is high in interpreting biopsy specimens from patients with dilated cardiomyopathy and that quantitative and standardized methods are needed to improve diagnostic consistency.