BACKGROUND:Psoriasis is a widespread, genetically determined immunemediated dermatosis of a multifactorial nature, characterized by a recurrent course with frequent associative damage to other organs and systems, which significantly reduces the quality of patients lives. For many years, phototherapy (PUVA and UVB-311 nm) has had one of the leading places in the treatment of moderate and severe psoriasis according to the world dermatological communities. However, with the advent of genetically engineered biological drugs, the frequency of its administration has significantly decreased.
 AIM:to evaluate the efficacy and safety of PUVA and UVB-311 nm in the treatment of moderate and severe psoriasis.
 MATERIALS AND METHODS:A retrospective study was conducted on the basis of the Federal State Institution Central polyclinic with the participation of 920 patients with moderate and severe psoriasis who received phototherapy (PUVA and UVB-311 nm) in the period from 2005 to 2021. The initial radiation dose was 0.51 J/cm2at PUVA and 0.10.2 J/cm2at UVB-311 nm with a gradual increase in the dose every 12 sessions by 0.5 J/cm2and 0.1 J/cm2, respectively. The treatment was carried out according to the method of four-time irradiation per week using the UV-7001K cabin (Waldmann, Germany).
 RESULTS:Among 920 patients there were 478 (52%) men and 442 (48%) women (aged 21 to 68 years). The average age of psoriasis onset is 345.2 years. The duration of the disease averaged 10.58.2 years. Vulgar psoriasis was observed in 756 (82%) patients, teardrop-shaped ― in 36 (4%), exudative ― in 73 (8%), inverse ― in 55 (6%). 249 (27%) were diagnosed with psoriatic arthritis. On average, the first phototherapy sessions were prescribed 2.11.6 years after the onset of the disease. The choice of phototherapy method depended on the severity of the process. Thus, with moderate psoriasis, patients were prescribed UVB-311 nm (n=473). The course consisted of 2535 sessions of radiation with a cumulative dose of 35.35.9 J/cm2. Clinical remission was observed in 93% of patients, significant improvement ― in 7%. The achieved clinical remission was maintained for 361194 days. In total, during the studied period, 149 people received 27 courses of UVB-therapy, 132 ― 24 courses, 53 ― 19 courses, 69 ― 15 courses, 58 ― 11 courses, 12 ― 7 courses. Multiple infiltrated plaques and refractory course of severe psoriasis was an indication for PUVA therapy (n=447). The course consisted of 2030 irradiation sessions with a cumulative dose of 81.514.3 J/cm2. Clinical remission was observed in 98% of patients, a significant improvement in 2%. 14 people received 23 courses, 21 ― 20 courses, 12 ― 19 courses, 227 ― 15 courses, 104 ― 13 courses, 33 ― 10 courses, 27 ― 4 courses, 9 ― 2 courses of PUVA. The achieved clinical remission was maintained for 420275 days. 12 (1.3%) patients cancelled PUVA prematurely due to the inability to take a photosensitizer. In other cases, the observed side effects were minor and did not cause discontinuation of therapy.
 CONCLUSION:PUVA and UVB-311 nm have demonstrated high efficacy and safety in the treatment of moderate and severe psoriasis. At the same time, it is necessary to conduct further research to improve the methods of phototherapy for faster achievement of long-lasting clinical remission, which will allow phototherapy to regain its leading position in the treatment of psoriasis, increasing the doctors trust and patients compliance.