Eccrine porocarcinoma is a rare malignant tumor arising from the intraepidermal ductal portion of the eccrine sweat gland (acrosyringium). It usually affects older persons and is located most commonly on the lower extremities. We describe a 55-year-old man with an aggressive metastasizing eccrine porocarcinoma diagnosed 10 years after the primary lesion. The metastatic lesions were located in the public area and scrotum and were associated with progressive lymphedema. Several biopsy specimens revealed numerous tumor cells in the dermis and especially in the lumina of lymph and blood vessels. Immunohistochemical studies showed staining with cytokeratin KL1, epithelial membrane antigen, Ca 15-3, and Ca 19-9. Vimentin, S-100 protein, neuron specific enolase, and carcino-embryonic antigen were negative. Treatment with carbon dioxide laser failed. The use of interferon alfa-2a for 9 months stopped progression of the tumor.