A 69-year-old women with malignant lymphoma (diffuse large:Working formulation) had associated with intracavital involvement of the right ventricle. The patient was referred to us for further examination with a diagnosis of heart failure. A tumor mass was detected by magnetic resonance imaging in the right ventricular outflow tract. While in the hospital the patient experienced cardiogenic shock due to neoplastic pulmonary embolism. The tumor was surgically resected and the patient was then treated with systemic chemotherapy. She went into complete remission and has continued in this state for six months. This case demonstrates that early diagnosis and intensive chemotherapy contribute to a good prognosis of patients with malignant lymphoma associated with massive involvement of a cardiac chamber. A review of the Japanese literature is presented.