Tumor necrosis factor-alpha (TNF-alpha) plays a fundamental role in the initiation and persistence of skin inflammation in psoriasis. The best evidence of the essential activity of this cytokine in the pathogenesis of psoriasis came from the observation that selective TNF-alpha blockers are dramatically effective in the therapy of this disease. The TNF-alpha inhibitors, infliximab and etanercept, have been employed with success in moderate to severe psoriasis and in psoriatic arthritis in randomized controlled trials. Anti-TNF-alpha biologicals induce rapid disease resolution and long-lasting remission, suggesting that they may alter the natural course of the disease. Further studies are warranted to more precisely establish the biological bases of the action of anti-TNF-alpha agents, better define which subgroup of patients can benefit most from this treatment, and the modalities of combination therapy with other antipsoriatic agents. Many other TNF-alpha inhibitors have been developed but none of them has been yet used in the therapy of psoriasis. Major limitations to the use of selective TNF-alpha blockers include the reactivation of latent tuberculosis, the risk of opportunistic infections, the development of specific antibodies, which is associated with a reduced duration of response to treatment, and the high cost.