OBJECTIVES: It was the clinical economic study comparing posaconazole and fluconazole or itraconazole for primary prophylaxis of invasive mycoses (IM) in patients with pronounced neutropenia in Russian economic circumstances using methods of mathematic modeling METHODS: Overall cost was calculated, including the cost of prophylaxis and treatment of IM and number of life-years saved for each group patients. To evaluate the degree of inaccuracy of the results, sensitivity analyses were performed. It was shown that the mean value of IM treatment costs (calculated as the mean of the costs of voriconazole, caspufungine, and lipid amphotericin B) in the posaconazole group was lower compared to the group of fluconazole/itraconazole. RESULTS: It was found that the difference was 0.94 with the less cost-requiring tactics of posaconazoole use. When the cost structure was studied in details it was shown that the group receiving posaconazole for prophylaxis had higher expenditures than the group taking fluconazole/itraconazole (12.9 times difference), due to higher posaconazole price. In the treatment of IM overall expenditures in the group of posaconazole were lower compared to those in the group of fluconazole/itraconazole (2.2 times difference), due to decreased risk of IM development in prophylactic use of posaconazole. The analysis of the main scenario demonstrates that the regimen of posaconazole use for prophylaxis was less expensive and more effective (dominating) compared to that with fluconasole/itraconazole. Alternative scenario analysis, where IM and mortality rates were equal in both groups of prevention, showed dominating character of posaconazole prophylaxis strategy. One-sided sensitivity analysis demonstrated that the rate of IM development when posaconazole was used for prophylaxis had more influence on incremental cost-effectiveness ratio, than the changes due to costs for antifungals purchase. CONCLUSIONS: Posaconazole prescription was economically beneficial compared to fluconazole/itraconazole for prophylaxis of IM in the studied patient population.