Crigler-Najjar syndrome type II is a rare familial disorder of bilirubin conjugation with consecutive life-long unconjugated hyperbilirubinemia. In the presence of severe hyperbilirubinemia, a fetus or an adult is at risk for neurological defects in this syndrome. This paper is the first report emphasizing details about this disorder in two patients from Turkey. The diagnosis was made on the basis of history and laboratory findings excluding other causes of unconjugated hyperbilirubinemia. Phenobarbital loading test and C bile analysis also supported the diagnosis. There was a study in the literature in which treatment with chlofibrate had been recommended in this syndrome. Based on the results of that study, we administered fenofibrate treatment to our patients for one month and analyzed serum bilirubin levels before and after this procedure. No improvement in bilirubin levels was observed in either case.