Inclusion Criteria:  Patients of both sexes. Diagnosed clinically with moderate to severe Psoriasis Vulgaris. patients able to swallow tablet and receive Narrow band Ultraviolet B phototherapy without any contraindication  Exclusion Criteria:  Pregnancy , lactation & women intent to become pregnant within 3 year after discontinuation of acitretin Patients with Hyperlipidemia Patients with mental problems and depression Patients with a history of malignancies, renal & liver diseases. Patients with a history of any inflammatory diseases as atopic dermatitis , asthma ulcerative colitis ) and Crohn's disease Patients received NB-UVB phototherapy in the last 6 months. Patients treated with methotrexate or biologic agents and any systemic treatment of psoriasis.