The Wolffian tumor, previously identified as "female adnexal tumor of probable Wolffian origin," is a rare tumor first described in 1973. The tumor is usually benign and is characterized by diffuse and tubular patterns, accentuated by reticulum and periodic acid-Schiff stains. Immunohistochemistry is used to further identify and classify these tumors, which are positive for cytokeratins, vimentin, inhibin, calretinin, and CD10 and negative for cytokeratin 20, epithelial membrane antigen, estrogen receptor, progesterone receptor, 34betaE12, and glutathione S-transferase. We report the case of a 47-year-old female with Wolffian tumor arising from the pelvic sidewall, separate from all reproductive organs. This is the first reported case of Wolffian tumor in this location.