Extramammary Paget's disease is a rare cutaneous adenocarcinoma, usually of epidermal origin and glandular differentiation and frequently associated with an underlying adnexal carcinoma and perhaps with underlying internal malignancy. We report a case of extramammary Paget's disease on the left with underlying internal malignancy. We report a case of extramammary Paget's disease on the (Korean J Dermatol 2001; 39(3): 357~360)