Psoriasis is now accepted as a T-cell-mediated disease and that targeting of T cell function and/or trafficking is a logical approach to therapy. As a consequence of recombinant DNA technologies biologic therapies are synthesisable in sufficient quantities for clinical use. The original proof of concept for T-cell-targeted therapies in psoriasis came with the demonstration that anti-CD4 monoclonal antibodies were effective. Progress is such that two T-cell-directed biologicals - alefacept and efalizumab - have recently been approved in the U.S.A. for the treatment of psoriasis. In addition to providing new therapies the T-cell-targeted biologicals with their selective approach can be used as sophisticated tools to dissect out and help our understanding of key pathomechanisms in psoriasis; the non - efficacy of anti - E-selectin is a case in point. It is likely that the most appropriate place for T-cell-directed biologicals in the management of chronic plaque psoriasis will be for maintenance, rather than induction, of remission. This is a reflection of mode of action and relative safety for long-term administration.