Multiple myeloma (MM) is a malignancy of the plasma cell characterized by migration and localization to the bone marrow where cells then disseminate and facilitate the formation of bone lesions. It is associated with a constellation of disease manifestations, apart from osteolytic lesions, anemia and immuno-suppression due to loss of normal hematopoietic stem cell function, and cardiac amyloidosis due to monoclonal immunoglobulin secretion as well[1]. Amyloid infiltration of the heart may frequently masquerade as hypertrophic cardiomyopathy (HCM). HCM, of which underlying cause and pathogenesis are largely unknown, is characterized by left and/or right ventricular hypertrophy, with predominant involvement of the interventricular septum in the absence of other causes of hypertrophy, such as hypertension or valvular heart diseases[2]. While excessive hypertrophy of the myocardium is most commonly associated with myocyte hypertrophy, infiltration with amyloid always needs to be considered. In this report we presented two cases of multiple myeloma that mimicked hypertrophic cardiomyopathy so closely that it required bone marrow or endomyocardial biopsy to establish the diagnosis. Multiple myeloma (MM) is a malignancy of the plasma cell characterized by migration and localization to the bone marrow where cells then disseminate and facilitate the formation of bone lesions. It is associated with a constellation of disease manifestations, apart from osteolytic lesions, anemia and immuno-suppression due to loss of normal hematopoietic stem cell function, and cardiac amyloidosis due to monoclonal immunoglobulin secretion as well [1]. Amyloid infiltration of the heart may frequently masquerade as hypertrophic cardiomyopathy (HCM). HCM, of which underlying cause and pathgenesis are largely unknown, is characterized by left and / or right ventricular hypertrophy, with predominant involvement of the interventricular septum in the absence of other of hypertrophy, such as hypertension or valvular heart diseases [2]. While excessive hypertrophy of the myocardium is most commonly associated with myocyte hypertrophy, infiltration with amyloid always needs to be considered In this report we presented two cases of multiple myeloma that mimicked hypertrophic cardiomyopathy so closely that it required bone marrow or endomyocardial biopsy to establish the diagnosis.