 Adalimumab, a fully human anti-tumor necrosis factor TNF monoclonal antibody has been approved for the treatment of moderate to severe psoriasis. However, in a portion of cases adalimumab does not induce reduction of psoriasis area and severity index PASI of 75 or greater, now being considered as gold standard for treatment efficacy. In this study we aim to determine in a randomized half-side comparison whether additional narrowband UVB-311nm phototherapy accelerates and improves the clearance of psoriatic lesions in adalimumab-treated patients after initial slow response. 