In a total of 339 patients with hypertrophic cardiomyopathies (typical HOCM, n = 224; atypical HOCM, n = 30; HNCM, n = 80) the clinical course, the Sokolow-Lyon index in the ECG and the prognosis as demonstrated by cumulative survival rates were analysed to get more differentiated information for the characterization of these myocardial disorders. No change in the type of hypertrophic cardiomyopathy was found, indicating different clinical entities. No increase of the Sokolow-Lyon index was observed during follow-up. Only a small proportion of patients seemed to benefit from treatment with propranolol. Surgical treatment appears to be the therapy of choice, at least in the advanced stage of the disease refractory to medical treatment. In addition, strong evidence was obtained that surgical treatment improved the prognosis in patients with typical HOCM.