The second step in the pathway for synthesis of bile acids from cholesterol is catalysed by the enzyme 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase. Deficiency of this enzyme has been reported to produce cholestatic liver disease with progressive cirrhosis. Treatment with chenodeoxycholic acid led to clinical and biochemical improvement in one patient. We report a further child with this disorder who presented with prolonged neonatal jaundice followed by symptoms of malabsorption of fat-soluble vitamins. Bile acid replacement therapy resulted in clinical and biochemical improvement; it was also possible to demonstrate improvement in the histological appearance of the liver biopsy 4 months after commencing treatment.