Large bile duct injury (that seen on cholangiography) is not usually considered a feature of autoimmune hepatitis (AIH) in adults but is present in up to 50% of children with AIH. The aim of this work was to study the prevalence of large bile duct abnormalities identified by magnetic resonance cholangiography (MRC) in adults given a diagnosis of AIH. Seventy-nine (n = 79) patients given a diagnosis of AIH (mean AIH score: 15.1 ± 3.4) were screened with MRC for evidence of sclerosing cholangitis (SC). Results were reviewed by two radiologists. Clinical parameters were correlated with MRC findings. A histological review of available liver biopsies (n = 29) was performed. Of the 79 patients surveyed, 8 (10%) had MRC findings consistent with primary sclerosing cholangitis (PSC). The interrater variability was excellent (kappa = 0.87). Younger age at diagnosis (24.3 ± 11.9), higher baseline alkaline phosphatase (186.4 ± 98.3), higher bilirubin at time of MRC (45.8 ± 37.2), and greater lobular activity on initial liver biopsy were significantly associated with the detection of this overlap of SC with AIH (P = 0.024, P = 0.037, P = 0.032, and P = 0.041, respectively), but not alkaline phosphatase/aspartate aminotransferase ratio, time between the initial diagnosis of AIH and the MRC, or the presence of cirrhosis on initial liver histology. Two cases with a normal MRC had histological lesions typical of small duct PSC. Conclusion: The presence of SC detected by MRC and from liver histology in adult patients with AIH may not be clinically overt, and thus the prevalence of this AIH/SC overlap may be higher than previously recognized. Our data suggest that routine radiological evaluation of the biliary tree should be performed in adults given a diagnosis of AIH, as in children the presence of this overlap negatively impacts on survival. (HEPATOLOGY 2008.)