 As many as 55 subjects 35 with BA or PSC and 20 Controls will be involved. We are also recruiting 20 adult patients with either BA, or PSC. The patients will be recruited from Lucile Childrens Hospital, Stanford Medical Center, and Stanford Redwood City Campus such as patients with primary sclerosing cholangitis, biliary atresia or other intestinal disorders for whom upper or lower endoscopy is indicated for routine medical management. There may be some participants who are over 18 years of age although the vast majority will be under 18. Vancomycin therapy will be administered to the BA patients 4 weeksand PSC patients. The PSC patient blood tests would now be done at various intervals: before starting the Vancomycin; every month until their Liver Function Tests are normalized; after their Liver Function Tests are normalized; before stopping the Vancomycin and after they are off the Vancomycin at month 1,3,6,12,and 24. Fecal samples will be taken. 