Recently, the autoimmune hepatitis (AIH)/primary sclerosing cholangitis (PSC) overlap syndrome has been reported increasingly. In this syndrome, patients present with features of both AIH and PSC. It has been suggested that the 2 diseases may be sequential in their occurrence, whereby patients have features of AIH and then after a number of years develop features of PSC, but clear confirmation of evolution has not been documented in adults. We describe 6 adult cases in which PSC was diagnosed many years after well-established AIH. Six patients are described in whom AIH definitely was diagnosed at presentation. No evidence of biliary disease was noted on the initial liver biopsy or endoscopic retrograde cholangiography (ERCP). All patients responded well to immunosuppressive therapy. After an average duration of follow-up of 4.6 years they became resistant to immunosuppression, and developed clear features of PSC, which was confirmed by ERCP in all patients. The average age of the patients at first presentation was 31.3 years, 2 were women and 4 were men, and 3 had ulcerative colitis. We found no specific features at presentation that could predict this evolutionary outcome. In conclusion, patients with well-established AIH can, after variable duration of follow-up, develop PSC. In patients with AIH who become resistant to immunosuppression of develop significant cholestasis, PSC should be ruled out by ERCP. (HEPATOLOGY2002;36:1393–1399).