Gilbert's syndrome is a benign condition characterized by asymptomatic sporadic episodes of jaundice, due to a mild unconjugated hyperbilirubinemia caused by a deficiency in bilirubin glucoronidation. Under certain physiologic or pathologic events bilirubin level rises but according to literature it does not reach out more than 3 mg/dl. We report 2 cases of Gilbert's syndrome, genetically tested, which presented with bilirubin levels above 6 mg/dl without any trigger or coexisting condition. In conclusion, bilirubin levels higher than 6 mg/dL in Gilbert syndrome are rare, hemolytic and other metabolism diseases must be ruled out, and genetic testing may be necessary in some cases.