Anti-heart antibodies detected by indirect immunofluorescence were found in the blood of persons deceased suddenly of heart failure more often (36,7%) than in those who died of other causes (16,6%). Antibodies were found the most frequently in rheumatic heart failure (50%), in other heart diseases (50%), and in ischemic heart disease (35,5%). In ischemic heart disease there was a high level of antibodies in patients with chronic heart aneurysm (66,6%) as compared with low level in those with acute infarction (16,6%). Obviously, antiheart antibodies often accompany a heart disease without being closely related to the heart failure. A negative result of serological examination does not exclude a heart disease.