A 13-year-old, male Maltese was refered to Veterinary Teaching Hospital of Konkuk University with inappropriate urination and hematuria. CBC, serum chemistry profile, urinalysis and urine culture were performed. Malignant cells were found in the urine sediment. Thoracic and abdominal radiography, retrograde positive-contrast cystography, retrograde double-contrast cystography, excretory urography, ultrasonography were performed. On the retrograde positive-contrast cystography examination, irregular filling defects were present on the left side of the cranial part of the bladder. Partial cystectomy performed and then medical therapy was conducted. On histopathological examinations, the lesion was confirmed as a transitional cell carcinoma of the urinary bladder.