Appendiceal adenocarcinoma is a rare malignancy for which there is no characteristic clinical presentation. We describe five women who presented with signs and symptoms characteristic of advanced ovarian cancer but whose final diagnosis was stage IV appendiceal cancer. Between 1998 and 1999, five women treated for presumed ovarian cancer were identified as having primary appendiceal cancer. Medical records and pathology were retrospectively reviewed. The median age was 47 years (range 36-61 years). All had elevated preoperative CA125 levels with a median value of 171 micro/ml (range 46-383). Four women underwent right hemicolectomy with two requiring radical surgical tumor debulking to render them optimally debulked. Four had postoperative chemotherapy, the most common agent used was 5-flourouracil. Median survival was 6.75 months (range 19 days-11 months). Primary adenocarcinoma of the appendix is rare; therefore, the clinical utility of radical tumor debulking and chemotherapy is not well described. Given the poor survival in our series, all efforts should be considered palliative. Although this disease process is uncommon, it should be entertained by gynecologic oncologists in the differential diagnosis of an intra-abdominal mass and ascites. The ability to make the correct diagnosis and differentiate between an ovarian and appendiceal primary is critical as the treatment modalities vary.