Alefacept, efalizumab, etanercept, and infliximab are currently approved for the treatment of adults with moderate to severe plaque psoriasis, and phase 3 trials for adalimumab are ongoing. The high level of evidence from large randomized, double-blind, placebo-controlled clinical studies for each of these biologics allows high-grade recommendations and helps define uncertainties, one of which is longterm safety. For tumor necrosis factor-a blocking agents, safety profiles are available from clinical experience in other indications. In general, biologics are safe and effective in the treatment of psoriasis, with potential to address unmet medical needs. Their distinct profiles allow dermatologists to match the biologic agent to individual characteristics of patients who are candidates for systemic therapy or phototherapy. In this evidence-based review of the literature, we assess the effects on psoriasis of induction therapy with 5 biologics and provide preliminary treatment guidelines.