Whether primary biliary cirrhosis (PBC) recurs after liver transplantation has remained an interesting and controversial issue; rejection, viral hepatitis, and drug effects all may mimic recurrent PBC histologically and biochemically. Furthermore, reliable clinical criteria for PBC recurrence are lacking. In this study, the issue of disease recurrence using a well-characterized monoclonal antibody (MAb), C355.1, that reacts with the immunodominant mitochondrial autoantigen of PBC (pyruvate dehydrogenase complex [PDC-E2]) was addressed. When used in an immunohistochemical assay, C355.1 produces intense apical staining of bile duct epithelium specifically in liver sections of patients with PBC and may be the earliest known marker of PBC. Immunohistochemical and histological analysis of serial liver biopsy specimens of 67 patients pre- and post-orthotopic liver transplantation (OLT), including 38 patients with PBC and 29 non-PBC liver disease controls, was performed. Sections were stained with MAb C355.1 or the control MAb C315 and analyzed to determine whether there was a recurrence of apical reactivity in the bile ducts of the posttransplantation biopsy specimens. The immunohistochemical staining was correlated with the histological findings and serum biochemistries at the time of the biopsy. Our data indicate that a significant number of patients who underwent transplantation for PBC (28 of 38) but not controls (0 of 29) develop a staining pattern of liver bile duct epithelium with MAb C355.1 that is indistinguishable from the pretransplantation pattern. Of the 28 patients with this apical staining pattern, 8 were characterized histologically as possible recurrent PBC, 2 as chronic rejection, 2 as acute rejection, 9 as nonspecific changes, 4 as normal or near normal, and 3 had other histological changes. Only 50% of the patients with apical C355.1 staining had liver enzyme levels suggestive of cholestasis. Thus, there appears to be immunohistochemical evidence that supports the concept of recurrence of PBC after OLT. The appearance of biliary epithelial abnormalities before the clinical appearance of disease is important not only for liver transplantation but also for understanding the natural history of PBC.