OBJECTIVES The incidence is 87% of hemophilia and often leads to disability (90% of patients). WHO recommends annual demand of 1 patient of 30 000 IU of factor VIII, but in Ukraine with a national program funded an average 5786 IU per year (20% of the need). In Ukraine, began production of the domestic drug factor VIII "BioKlot A" from 2012. The aim was to determine the effectiveness of substitution treatment “BioKlot  A“ native medicine in the treatment of patients with hemophilia A. METHODS In a pilot clinical study examined 168 patients diagnosed with hemophilia A severe form of male, aged 18-52 years, who were hospitalized. Experimental group received “BioKlot A” control group – “Oktanat” in equal doses of 40 IU / kg / day during the first day, 20 IU / kg / day - the next day. All patients were determined by the intensity of joint pain, joint swelling index, joint circumference, blood count, and others criteria. RESULTS Within 24 hours after “BioKlot A” (average dose rate of 10 000 IU) joint pain significantly decreased after 48 hours - the pain disappeared and the joint volume decreased by 14% in 72 hours - the amount of diminished joint by 22% and increased range of motion by 28%. Time coagulation by Lee-White 24 hours decreased from 30 ± 0,2 minute to 19 ± 0,2 minute.In the control group, the average dose rate amounted to 10750 IU “Oktanat” and dynamics of clinical and hematological data were not significantly different from the experimental group. CONCLUSIONS The established similar effectiveness of factor VIII “BioKlot A” (Ukraine) and “Oktanat” (Austria) with clinical and laboratory criteria. Production of factor VIII preparation in Ukraine has significant socio-economic impact, providing improved quality of life of patients.