The mediastinal tumors are rare but potentially fatal diseases. Teratomas are derived from multipotent germ-line cells. In majority of cases mediastinal tumours are incidentally detected on chest X ray. We present 19-year-old patient with recurrent pericarditis recurrent pericarditis. After comprehensive diagnostic process it was figured out that the reason for recurrent pericarditis was large mediastinal teratoma. Once the correct diagnosis has been made, the patient could have been completely cured. JRCD 2014; 1 (6): 29–32