A seven year old, castrated male Boxer dog presented to the Cornell University Hospital for Animals soft tissue surgery service on July 28, 2009 for evaluation of renomegaly and hematuria of three months duration. Abdominal ultrasound revealed renomegaly of the right kidney with complete loss of normal renal architecture. An ultrasound guided fine needle aspirate was taken of the right kidney for cytology which showed abnormal cells consistent with carcinoma. Based on a presumptive diagnosis of renal carcinoma, a right sided ureteronephrectomy was performed on August 3, 2009. Histologic evaluation of the right kidney gave a definitive diagnosis of well differentiated tubular renal adenocarcinoma. The dog was discharged on August 7, 2009 with a guarded prognosis. Renal carcinoma is a malignant, locally aggressive neoplasm that can metastasize to lungs, liver, and other abdominal surfaces. Surgery is the most widely accepted treatment modality however it is rarely curative even when the tumor appears localized at the time of excision.