Background/Aim. Bacterial contamination of blood components, primarily platelet concentrates (PCs), has been identified as one of the most frequent infectious complications in transfusion practice. PC units have a high risk for bacterial growth/multiplication due to their storage at ambient temperature (20 ± 2°C). Consequences of blood contamination could be effectively prevented or reduced by pathogen inactivation systems. The aim of this study was to determine the Mirasol pathogen reduction technology (PRT) system efficacy in PCs using an artificial bacteria-contamination model. Methods. According to the ABO blood groups, PC units (n = 216) were pooled into 54 pools (PC-Ps). PC-Ps were divided into three equal groups, with 18 units in each, designed for an artificial bacteria-contamination. Briefly, PC-Ps were contaminated by Staphylococcus epidermidis, Staphylococcus aureus or Escherichia coli in concentrations 102 to 107 colony forming units (CFU) per unit. Afterward, PC-Ps were underwent to inactivation by Mirasol PRT system, using UV (l = 265-370 nm) activated riboflavin (RB). All PC-Ps were assayed by BacT/Alert Microbial Detection System for CFU quantification before and after the Mirasol treatment. Samples from non-inactivated PC-P units were tested after preparation and immediately following bacterial contamination. Samples from Mirasol treated units were quantified for CFUs one hour, 3 days and 5 days after inactivation. Results. A complete inactivation of all bacteria species was obtained at CFU concentrations of 102 and 103 per PC-P unit through storage/ investigation period. The most effective inactivation (105 CFU per PC-P unit) was obtained in Escherichia coli setting. Contrary, inactivation of all the three tested bacteria species was unworkable in concentrations of ≥ 106 CFU per PC-P unit. Conclusion. Efficient inactivation of investigated bacteria types with a significant CFU depletion in PC-P units was obtained - 3 Log for all three tested species, and 5 Log for Escherichia coli. The safety of blood component therapy, primarily the clinical use of PCs can be improved using the Mirasol PRT system.