Psoriasis is an immune-mediated inflammatory disease that mainly involves the skin but may accompany many systemic comorbidities. Topical, systemic, conventional or biological drugs are used in the treatment of the disease. In recent years, some critical cytokines have been shown in pathogenesis of the disease. These cytokines act in the cell by using the JAK-STAT pathway. Many clinical studies have been conducted with small molecules that inhibit this intracellular signaling pathway, and successful results have been obtained with some of them. In this section, JAK-STAT inhibitors used in treating psoriasis and related trials are discussed.