We describe two children with a severe combined immune deficiency (SCID) with B cells. Following a T-cell-depleted haploidentical bone marrow transplantation (BMT), they both developed a chronic graft-versus-host disease (GVHD) of the skin and a severe persisting hyperbilirubinaemia and elevated liver enzymes. The diagnosis of a vanishing bile duct syndrome was confirmed by liver biopsies. Because corticosteroids and cyclosporin A induced only a partial response, ursodeoxycholic acid (UDCA) was added to their treatment schedule. Serum bilirubin and liver enzymes returned to normal within months. A control liver biopsy showed normal and proliferating bile ducts without cholestatic damage. We conclude that UDCA was well tolerated and may be of value as an additional treatment for hepatic GVHD in SCID.