In the period 1998-, we registered four sudden and unexpected cardiac deaths in male athletes due to myopericarditis during or after physical exercise. Three of them were professional soccer players and the fourth was engaged in swimming. One aged 29, had symptoms of tiredness, heart enlargement and left ventricular premature beats during training. Three of them, aged 17-18-18, were without symptoms. Three died during training and the fourth died in the hospital after head trauma at training. In the first one, aged 29, forensic autopsy showed chronic myopericarditis, thickening of the left ventricular wall of 15 mm and enlargement of the whole heart. The second one, aged 17, had subacute diffuse myopericarditis, suppurative tonsillitis and narrowed ascending aorta. The third, aged 18, had chronic myopericarditis and cardiac aneurysm of the left ventricle. The fourth, aged 18, had fibrinous pericarditis, thickening of the left ventricle 20 mm, hypoplastic ascending aorta, bilateral bronchopneumonia and cerebral contusion with edema. In Croatia, death rate among athletes, including all its causes, reached 0.15/100,000, in athletes suffering from myopericarditis it was 0.34/100,000, in others who practice exercise recreatively it amounted to 0.57/100,000 (p=0.0068), and in all males who practice exercise it measured 0.75/100,000 (p=0.0014). Physical exercise has to be contraindicated in cases of myopericarditis for at least six months from the onset of the illness.