Gilbert's syndrome (GS) is a benign and inherited state characterized by mild, lifelong, unconjugated hyperbilirubinaemia in the absence of haemolysis or evidence of liver disease. Its molecular basis, mutations in the TATA box upstream of the uridine diphosphoglucose glucuronyltransferase gene, leads to impaired bilirubin glucuronidation. This synopsis outlines the pathophysiology and investigation appropriate for this innocent anomaly.