A 1-year-old, female, previously spayed domestic shorthair cat presented with abnormal behavior characterized by rubbing up against objects, vocalization and abnormal body posture. A diagnostic laparoscopy was performed and a dilated segment of the left uterus and ovary was found in association with ipsilateral renal agenesis. Papillary hyperplasia of the endometrium of the dilated segment was found on histopathology. The occurrence and findings of this condition are reviewed.