An unusual case of primary adenocarcinoma occurring in the inguinal region of an elderly woman is reported. It appeared to have arisen from the mesothelium of the canal of Nuck. It recurred and involved one inguinal lymph node three years after the diagnosis and seven years after the initial appearance of the mass. The absence of associated peritoneal tumor distinguishes this case from other reported primary malignant neoplasms of the hernial sac.