In this case report, we aimed to report of clinical, ultra so nog raphical and biochemical findings of naturally occurring radiofucent gallstone and efficacy of treatment with urcedeoxicolic acid in a dog. An 11-years-old. female Collie dog referred with a history of anorexia, lethargy and vomiting was Included in the present article. At physical examination, crania! abdomen pain was detected on palpation. Biochemical analysis of the blood serum revealed urea 28 mg/dl, creatinin 0,9 mg/dl. ALT 50 IU/L, ALP 350 IU/L, AST 300 IU/L. GGT 71 IU/L, total bilirubin 0.5 mg/dl. direct bilirubin 0,4 mg/dl, indirect bilirubin 0.1 mg/dl. cholesterol 350 mg/dl and trigllserid 215 mg/dl. Ultrasonographical examination revealed hyperecogenic liver parenchyma, bile duct and gall bladder wall and inside the bladder a 9 mm diameter radi olu cent mass without acoustic shadowing artifact. Based on clinical, laboratory and ultrasonographical examination, radiolucent gall stone and cholangitis were diagnosed. Therapy included ampicilin+sulbactam at a dosage of 25 mg/kg twice a day i m., for 15 days, metronidazole at the dosage of 10 mg /kg q 12 h, metoclopromide 2 mg/kg i.m., q 12 h, ursodeoxycholic acid at the dosage of 10 mg/kg once a day per orally for 1 month. End of the thirty day hepatic parenchyma and bite ducts were norma! and no mass was detected on the ultrasonographic examination of the bladder. Biochemical analysis revealed ALP 100 IU/L, AST 80 IU/L. ALT 30 IU/L, GGT 7 IU/L, cholesterol 164 mg/dl and trigliserit 145 mg/dl.