In order to detect and quantify intrapulmonary shunts in children with liver disease, a radionuclide method was developed and evaluated in such a population. METHODS We studied 135 children in whom the severity of liver disease, in most cases, justified consideration of liver transplantation. Patients were separated into two groups according to their resting PaO2 values under room air: 109 children were normoxic and 26 were hypoxic. A radionuclide scan was performed immediately after intravenous injection of human albumin macroaggregates. Activity of the lungs (L) and brain (B) was counted. A shunt index (SI) was calculated as SI = 100.B/L. We compared this index with blood gases and clinical follow-up. RESULTS In the normoxic group, SI was 0.43 +/- 0.30 (mean +/- s.d.); none of the 102 children with SI < 1 developed hypoxemia during their follow-up. Two of the six children with SI > 1 developed subsequent hypoxemia. In the hypoxic group, the nine children with SI < 1 did not aggravate their hypoxemia during follow-up. The 17 hypoxic children with SI > 1 later developed severe hypoxemia. CONCLUSIONS Scintigraphy with intravenous human albumin macroaggregates is more accurate than measuring arterial blood gases to detect IPS in children with cirrhosis.