The hepatic clearance of Tc-99m labeled iminodiacetic acid (IDA) compounds is believed to be impaired in patients with severe hyperbilirubinemia. Competitive inhibition of hepatocyte uptake of IDA by bilirubin has been demonstrated in vitro, but not by clinical scintigraphy. We present a patient with Crigler-Najjar syndrome without evidence of hepatobiliary damage, who demonstrated normal uptake and excretion of Tc-99m DISIDA despite a serum indirect bilirubin level in excess of 30 mg/dl. It is therefore suggested that a markedly elevated serum bilirubin level per se does not inhibit hepatic uptake of Tc-IDA and does not preclude clinically useful scintigraphic examination.