OBJECTIVES: To model cost utility of human leukocyte transfer factor for parenteral use (TF) in adult and pediatric patients suffering from cellular immunodeficiency (CID), based on effectiveness data from retrospective study observing decreasing frequency of respiratory (RTI) and/or urinary (UTI) tract infections, prostatitis and/or vulvovaginitis episodes. METHODS:  The decision tree model developed in Excel using real world data from an observational multicenter retrospective realized in the period from July 2014 to December 2014 in 14 centers in Slovakia. The primary objective was to evaluate the cost utility based on effectiveness by assessment of the number of documented infections over one year since start of the treatment as compared to the last year of the pre-treatment period. The systematic review was run to get utility value for RTI, UTI, prostatitis and vulvovaginitis episodes. RESULTS:  Calculated incremental cost utility ratio was 6.639,25 €/QALY based on the sample (181 patients) was predominantly female (74,6 %) and the average age was 44 with a range of 6 to 82. The most common recurrent episodes were RTI occurring 558 times at average in the year before TF initiation, followed by UTI and vulvovaginitis episodes. The significant reduction was observed in RTI, UTI and vulvovaginitis episodes after treatment with TF. Respiratory tract infection where reduced from 558 to 184 a year before versus after initiation of TF application (p‑valuemax≤0,025). Significant reduction was achieved in UTI and vulvovaginitis episodes. Moreover lower resource use was measured in the need of antibiotic treatment and hospitalizations. Univariate sensitivity analysis was run based on Slovak guidelines with the result 4.647,48 – 9.484,65 EUR/QALY. CONCLUSIONS:  The calculated cost utility ratio together with the real world data about the reduction of recurrence of infection`s episode in adult and pediatric patient with CID show that treatment using human TF is cost effective below the threshold set in Slovakia.