The study presents the results of combined usage of narrowband UVB phototherapy with low — dose methotrexate in treatment of psoriasis. 48 patients with moderately severe and severe psoriasis in the phase of progression accompanied by psoriatic arthritis have been observed. 30 patients were treated with UVB therapy with a 311 nm narrowband in combination with low doses of methotrexate (7.5 mg per week). Photobox Waldmann 7002 K (Germany) with TL-01 lamps which generate radiation in 310 – 315 nm wavelength range with maximum 311 nm wavelength emission. The procedures have been carried out 4 times a week. Methotrexate should be received as tours 7.5 mg once a week, according to Weinstein — Frost scheme under the supervision of laboratory parameters. The treatment course consists of three tours. Treatment has been carried out on a background of traditional therapy.The comparison group received conventional therapy in combination with narrowband UVB phototherapy and nonsteroidal anti-infammatory drugs. Evaluation of the effectiveness of the therapy was based upon dynamic assessment of PASI and DLQI indexes and proved by earlier reduction of clinical symptoms than in the comparison group, which resulted in reduction of absolute PASI and DLQI values. No adverse effects caused by the therapy undertaken have been noted. The results of the study appear to prove safety and effectiveness of such therapy in treatment of psoriasis.