Between 1986 and 1989 there were 9 cases of idiopathic congestive heart failure at this clinic. Normally heifers in the last 1/3 of pregnancy and young cows aged between 2.5 and 3.5 years were affected, but the disease also occurred in one younger (1.5 years), one older (6 years) and in one male animal. In contrast to other reports, myocardial fibrosis in the State of Hesse was only seen in the Rotbunte breed. The animals suffered from a severe heart failure with venous congestion and congestive edema of the brisket, the submandibular area and the ventral abdomen. In most cases there is no precise difference in history, clinical findings and laboratory findings between myocardial fibrosis, traumatic pericarditis and endocarditis valvularis. Only pathological and histological examinations of the heart confirm a suspected myocardial fibrosis: The heart is enlarged and dilatated and seems to be non-elastic. Microscopically a scattered interstitial fibrosis and signs of myocardial degeneration are visible.