Most autoimmune diseases (ADs) are still associated with high morbidity and mortality despite the use of a wide range of drugs that can delay their progression, control their symptoms, but never bring about a complete cure. This failure has aroused interest in new forms of monoclonal antibody-based experimental immunotherapy (IT), aiming at targeting cellular antigens or cytokines involved in the pathogenesis of ADs. The first part of this review offers a general overview of the molecular mechanisms that mediate the immune response and the molecule regarded as potential IT targets. A critical evaluation will then be made of some forms of IT, with particular emphasis on TNF-alpha and CD20-blocking reagents. Lastly an account will be given of active IT whereby an endogenous response against antigens regarded as the target of passive IT can be induced by anti-idiotype or peptides.