Background. The implementation of new FLT3-targeted drugs in clinical practice has changed the approaches to the management of patients with acute myeloid leukemias (AML) with FLT3 mutation. One of these drugs is gilteritinib, approved by FDA in 2018 as a drug of choice in the therapy of adult patients with relapsed/refractory AML with FLT3 mutation. Aim. To assess the economic feasibility of gilteritinib in the therapy of adult patients with relapsed/refractory AML with FLT3 mutation. Materials & Methods. Pharmacoeconomic modelling was based on Markov and decision-tree models. Incremental cost-effectiveness ratio (ICER) was calculated relative to the efficiency indicator “overall survival”. Its values were compared with those calculated for venetoclax as reference drug, which has been already included in Essential Drug List and used as a first-line drug in this population if high-dose chemotherapy therapy is contraindicated. A Budget Impact Analysis has been made. Results. Gilteritinib proved to be not only more effective in terms of overall survival (median 9.3 vs. 5.6 months), but also more cost-intensive (7,408,108 vs. 1,685,356 rubles a year) compared to the currently used polychemotherapy regimens. However, the difference of ICER with venetoclax was +4.89 % of total costs. The Budget Impact Analysis showed that the total economic load of implementing gilteritinib in clinical practice throughout 3 years will be 8,628,658,505 rubles. Conclusion. Gilteritinib therapy is economically feasible and viable for adult patients with relapsed/refractory AML with FLT3 mutation.