Efalizumab, one of a new generation of biological agents, has been approved for use in moderate to severe psoriasis in over 35 countries including Canada. It may hold the promise of a new level of safe, long-term disease control for psoriasis patients, who have had few adequate options to date. Dermatologists and other caregivers may require some background regarding the mechanisms of action and the optimal use of this drug before integrating it into their standard repertoire of treatment. The present supplement discusses efalizumab's biological basis and reviews its clinical safety and efficacy. The salient differences amongst the various biologicals, with regard to safety, efficacy and convenience, are also considered. The supplement concludes with a practical guide to initiating and maintaining patients on efalizumab treatment.