OBJECTIVE: To report a case of extrinsic ureteral obstruction arising from mucocele of the appendix and review the clinical, diagnostic and therapeutic aspects of this appendiceal pathology of interest in urology.METHODS: A 71-year-old female patient that had previously undergone radical gynecological surgery and postoperative radiotherapy presented with right lumbar pain. Patient evaluation by ultrasound, IVP and CT showed a pelvic mass causing right extrinsic ureteral obstruction. Release and reinsertion of the right ureter and appendectomy were performed. RESULTS: The anatomopathological study showed an appendiceal mucinous cystadenoma. The patient is asymptomatic after surgery.CONCLUSIONS: Appendiceal mucocele is a dilatation of the vermiform appendix due to collection of mucoid material that is frequently produced by a cystadenoma. The presenting feature is usually that of acute appendicitis. The definitive diagnosis is based on the anatomopathological findings. Treatment is by appendectomy for the benign tumors and by right hemicolectomy in a second stage procedure for malignant tumors. This appendiceal pathology should be taken into account in the differential diagnosis of right extrinsic ureteral obstruction.