A six-year-old neutered female albino ferret was presented with an acute episode of lethargy and anorexia. Clinical examination revealed marked cranial abdominal pain. A severe neutrophilic leukocytosis was present. Abdominal ultrasound was consistent with a diffuse peritonitis and severe bile duct inflammation. Cytology of the abdominal effusion revealed bile peritonitis. An exploratory laparotomy was performed and the gall bladder appeared inflamed with multiple perforations. A cholecystectomy was performed. The ferret recovered without complication. Bacteriological culture of the bile and gall bladder yielded a pure growth of Pseudomonas aeruginosa. Histopathological analysis of the gall bladder and liver was consistent with a marked cholecystitis and cholangiohepatitis. On the basis of sensitivity testing, the ferret was treated with marbofloxacin for one month. No complications or reoccurrence were seen up to 1 year after the diagnosis. To the author's knowledge, this is the first report of bile peritonitis secondary to gall bladder rupture in a ferret.