A 4-year old male Pitbull terrier dog was presented with a history of nasal discharge of left side and dyspnea for 3 days. This dog had a bitewound on the head due to dog-fighting two weeks ago. There was no abnomality except mild anemic sign on blood examination. Frontal projection of radiographs was taken. This was diagnosed as frontal sinusitis. After skin incision on frontal head, a silicone tube was inserted into the affected frontal sinus. Abscess of the frontal sinus was drainaged and irrigated with saline solution containing trypsin and cephazolin. This patient who also treated with enrofloxacin was recovered completely.