We report a case of papillary eccrine adenoma occurring in a 39-year-old male who had a walnut sized, firm nodule on the right knee without subjective symptoms. Histopathologic exammination revealed a well circumscribed, non-capsulated dermal nodule consisting of multiple ducts with various sizes. These ducts were composed of double layered epithelial cells in most areas, but in some areas severe intraluminal papillation snd pseudostratification into the lumen were seen and the lumina were filled with a homogenous eosinophilic substance and partially with calcium deposition. Immunohistochemical studies with S-100 antigen and csrcinoembryonic sntigen (CEA) were also performed. Positivity for these sntigens strongly supports the hypothesis that this unusual neoplasm differentiates toward the eccrine secretory coil. (Kor J Dermatol 28(1): 107 lll, 1000)