Patients will be randomly assigned (1:1:1 ) either to ; NB-UVB photo-therapy alone , Acitretin therapy alone or NB-UVB photo-therapy combined with Acitretin therapy randomization will be done by closed envelopes . investigator will be blinded to study drug assignment , while patients and data interpreter will not be masked to study drug assignment.

Study Setting: Qena University Hospital, Department of Dermatology ,Venereology& Andrology.

Study subjects: the study will include psoriasis Vulgaris patients who Come to the out patients dermatologic clinic and matching inclusion & exclusion criteria as follow, from 9/2021 up to 3/2023 and then patients will be divided to each group equally as follow:

Group 1: Patients will be treated with NB-UVB phototherapy 3 sessions weekly for 3 months with maximum dose of 1400 mJ/cm2.

Group 2: Patients will be treated with Acitretin in dose of 0.5-1 mg per kg per day orally for 3 months Group 3: Patients will be treated with Acitretin in dose of 0.5-1 mg per kg per day orally plus NB-UVB phototherapy 3 sessions weekly for 3 months with maximum dose 1400 mJ/cm2.

Group 4: 30 healthy individuals un related , age, sex , BMI matched with volunteers.

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.