Etanercept, a biological antipsoriatic drug with anti-tumor-necrosis factor (TNF) activity has been approved for the treatment of moderate to severe psoriasis. However, in a substantial portion of cases etanercept does not induce reduction in psoriasis area and severity index (PASI) of 75% or greater, now being considered as gold standard for treatment efficacy. In this study the researchers aim to determine in a randomized half-side comparison, whether additional narrowband UVB-311nm phototherapy accelerates and improves the therapeutic efficacy of etanercept.