Abstract: Introduction: Psoriasis is a chronic residive inflammatory skin disease that can occur in all age, characterized with erythematous plaque and thick scales. Interleukin-22 (IL-22) is a cytokine pro-inflammatory that has an important role in inflammatory diseases. IL-22 induces migration of keratinocytes, causing hyperplasia of the keratinocyte layer resulting in thick epidermis. There was correlation between expression IL-22 with psoriasis severity.