SUMMARYBlunt chest trauma causing isolated right atrial tear and cardiac tamponade in three patients is reported. All three patients presented with hypotension, elevated central venous pressure and altered consciousness. Echocardiographic examination demonstrated pericardial effusion in all three cases. All three patients underwent operation with a median sternotomy approach without using cardiopulmonary bypass. At operation, two patients had one tear in the right atrium, the other had two tears in the right atrium. All three patients recovered uneventfully. Early use of echocardiography to detect the presence of hemopericardium and cardiac tamponade in patients with suspected atrial rupture following blunt chest trauma is advocated. (Jpn Heart J 2000; 41: 535-540) Key words: Blunt cardiac injury, Atrial tear, Cardiac tamponade BLUNT chest trauma causing cardiac chamber rupture is rare and carries a high mortality rate. It is estimated that cardiac chamber rupture occurs in 10 to 15% of victims of fatal vehicular accidents. 1) Blunt traumatic ventricular rupture tends to be rapidly fatal and few patients survive. In contrast, blunt traumatic atrial tear tends to have a better prognosis than ventricular tear.2,3) However, the clinical manifestations of blunt traumatic cardiac chamber rupture are usually subtle, and unless the physician has a high index of suspicion, the diagnosis can be missed, resulting in delayed treatment and increased mortality. Herein, we present three cases with blunt traumatic right atrial tear that were successfully treated with cardiorrhaphy.