This review reconsiders how the Th1/Th2 paradigm can be applied to Th1-mediated autoimmune disease. Although there is evidence that autoimmune diseases such as multiple sclerosis, type 1 insulin-dependent diabetes mellitus, and posterior uveitis are Th1 mediated and that in some cases reduction of the Th1 response or a Th2 type shift may alleviate disease, many apparent exceptions are now well documented. These exceptions center around the contradictory actions of the Th1 cytokine IFN-gamma and the evidence that Th2 lymphocytes can also cause disease. Recent information on the regulation of Th1 and Th2 lymphocytes in terms of the innate immune response and by other T cells helps to clarify the reasons for some of these discrepancies and enables the Th1/Th2 concept to be accepted as an integral part of the complex interactions occurring as autoimmune disease develops.