Merkel cell carcinoma is a rare, aggressive neuroendocrine tumor of the skin commonly seen in the elderly on the head, neck and extremities, with a predisposition for local regional and distant spreading. A case of Merkel cell carcinoma occurred in a woman treated with immunosuppressive therapy for myasthenia gravis, is described and the possibility of a link between the immunosuppressive and/or oncogenic therapy and this tumor is suggested.