Primary sclerosing cholangitis (PSC), although uncommon, is a devastating and insidiously progressive liver disease, resulting from advancing inflammation, fibrosis and obliteration of the bile ducts in the liver, leading to cirrhosis and end-stage liver disease. Although prognosis in children may be somewhat better than that of adults, approximately one third of pediatric patients require transplantation by adulthood. Other than transplantation, there is to date no therapy conclusively proven to improve the long-term outcome. Ursodeoxycholic acid (UDCA) improves biochemical markers of liver disease, although in high doses does not clearly improve the long-term outcome in adults, and in a recent study may have actually worsened outcome. Childhood PSC is different from that of adult PSC in many ways, and children may derive more short-term, as well as long-term, benefit than adults. This unique multicenter study will carefully monitor the effects of withdrawal and restarting UDCA on liver injury and inflammation in children with PSC. The preliminary data will help in the design of a more definitive larger study to determine if UDCA has a beneficial role in the treatment of PSC in children.