Hypothyroidism is the leading cause of thyroid dysfunction and can be seen in up to 40% of these patients and appropriate treatment is critical importance [1,2]. Hypothyroidism is seen most frequently in patients receiving total body irradition (TBI) containing conditioning regimens. Hypothyroidism may be seen in cases receiving chemotherapyonly conditioning regimens but less frequently [3,4,5]. Here we report a case of hypoythyroidism detected 6 months after autologous hematopoietic stem cell transplantation (HSCT) for multiple myeloma (MM).