Psoriasis is a chronic inflammatory disease that affects 2% to 4% of the population; about 20% of the patients present a moderate-to-severe form. The IL-23/Th17/IL-17 molecular axis is considered crucial in the pathogenesis of psoriasis and IL-17 is fundamental in the maintenance of the immune and inflammatory alterations causing psoriasis. Expression of IL-17A, IL-17F, and IL-17C is strongly increased in psoriatic plaques. Effective therapy leads to restoration of the expression of a wide range of genes (including effector cytokines and chemokines downstream of IL-17) to near normal levels. Brodalumab is the first biologic drug targeting specifically the subunit A of the IL-17 receptor (IL-17RA) and thus inhibiting not only IL-17A but also other members of the IL-17 family. Brodalumab is very effective and safe in treating moderate-to severe psoriasis.