BACKGROUND AND OBJECTIVES: Primary adenocarcinoma of the appendix is rare, which makes an understanding of its natural history difficult. To date, it is treated predominantly with surgery alone. This review aims to elucidate the patterns of failure and treatment outcomes when adjuvant treatment is given after primary surgical resection. METHODS: Twenty-three patients were treated with either surgery alone, or with surgery and adjuvant radiation +/- chemotherapy. A review of the clinical course of these patients was undertaken with an analysis of the local control, distant failure, disease-free survival, and overall survival. RESULTS: Most patients presented with local invasion or metastatic disease often involving the peritoneum. Overall survival was 32%, similar to the results of other studies. Analysis of patients with locally advanced disease showed improvement in overall survival and local control with postoperative radiation therapy compared to surgery alone. CONCLUSIONS: Adenocarcinoma of the appendix is a rare disease that presents most often in an advanced stage. It has been shown by others that a right hemicolectomy provides the best outcome with respect to surgical procedure. Postoperative irradiation appears to provide a benefit for both local control and overall survival.