A 39-yr-old, acyclic, uniparous, female white rhinoceros with a history of recurrent vaginal bleeding was euthanized following a period of respiratory distress and ill-thrift. The rhinoceros' uterus had previously been evaluated by ultrasound and diffuse endometrial hyperplasia and two benign uterine leiomyomas had been diagnosed. At necropsy examination, a large, infiltrative, metastatic uterine adenocarcinoma was found multifocally throughout the uterus, scattered within the peritoneal cavity, on the diaphragm, the splenic capsule, the pleural surface of the lung and mesenteric lymph nodes. A large volume (100 L) of ascites fluid was present in the abdominal and pleural cavities.