and previous biological treatments. The effectiveness variables are affected body surface area (BSA) and psoriasis area severity index (PASI) AND 90% PASI clearance (PASI90) collected at baseline, and next visits with dermatologist. The main tools used: Diraya© for the clinical history, Modulab© for laboratory values and Excel© for anonymised data recording. The information was collected according to data minimisation policy, article 5.1 of data protection. Results 49 patients (29 men) included with a mean age of 50.9 years. The main biologic pre-treatments were etanercept (31), adalimumab (11), secukinumab (9) and ustekinumab (9). Averaged pre-treatment BSA (13,6 ± 10.27 SD) and PASI (9.7 ± 6.68 SD). Next dermatologist's control at 5 months 43 patients averaged BSA (3.9 ± 9.27 SD) and PASI (2.9 ± 4.17 SD). PASI90 was reached by 48.8% of patients. There were four treatment discontinuities during this period (1 due to lack of adherence, 1 due to primary failure, 1 due to secondary failure and 1 due to toxicity). At 10 months 25 patients averaged BSA (1.8 ± 3.28 SD), PASI (1.8 ± 3.30 SD), and PASI90 was reached by 72%. 3 treatment discontinuities in this period (1 due to gestational desire and 2 due to secondary failure). At 18 months 15 patients averaged BSA (0.9 ± 1.55 SD) and PASI (0.5 ± 0.91 SD). PASI 90 was reached by 73%. Patients not counted had not gone to dermatology control yet when our analysis were made. Safety: One patient had to stop treatment due to strong diarrhoeas after each dose. Conclusion and RelevanceAccording to the results obtained, it is possible to evaluate guselkumab as an effective and safe alternative in the treatment of moderate to severe psoriasis resistant to conventional treatments.