We report two cases of hemopericardium occurring in seven-month-old and 12-year-old boys, who had no history of major trauma. The possible cause of the hemopericardium for the infant was falling from a bed which was 75 cm high two weeks prior to the admission. The 12-year-old boy had fallen from a chair and damaged his chest 4 weeks previously. Their coagulation tests were all normal. By means of pericardiotomy, we drained 120 ml and 1200 ml of blood, respectively. The boys have now been well over follow-up periods of 24 and 18 months, respectively.