While fervently studied by several laboratories, the role of T cells in the pathogenesis of primary biliary cirrhosis (PBC) still remains a mystery. The studies concerning cell phenotype, antigen specificity, and major histocompatibility complex (MHC)-T-cell receptor (TCR) interaction gathered thus far all address important aspects of this intriguing conundrum. However, the lack of an animal model and the genetic diversity of the human population with PBC make this task even more difficult. The possibilities regarding immune therapy resulting from such studies are of great importance. Future work concerning the T-cell epitopes-for both the pyruvate dehydrogenase complex (PDC), its related mitochondrial autoantigens, and any as yet unidentified PBC-specific autoantigens-may provide valuable information with regard to disease therapy. In addition, knowledge with regard to TCR usage and MHC association will help to clarify the pathogenic mechanisms of this enigmatic disease.