A 37y/o male developed mass formation in right tibia in Oct. 1986. He had generalized lymphadenopathy. Diagnosis of malignant lymphoma of B cell type (follicular, large cell type) stage IV B was made because of bone marrow involvement. Surface marker analysis of pathologic cells in the peripheral blood, bone marrow, lymph nodes revealed that they were of B cell type with positive EA gamma rosette formation, positive surface immunoglobulin with IgM-kappa and cytoplasmic immunoglobulin with IgM-kappa and positive responses to monoclonal antibodies of OKIal and B1. He responded partially to VEPAM therapy but in Jan. 1987 he developed Ga accumulation in heart and ECG abnormalities such as depression of ST and inverted T in II, III, AVF, V1-V6 leads. After treatment with VEP, ECG abnormalities disappeared in a month. The same ECG abnormalities recurred once more and disappeared again. Autopsy findings revealed accumulation of lymphoma cells in epicardium and myocardial degeneration in right ventricle. Ga scan appears to be a valuable method for detection of early cardiac involvement by malignant lymphoma.