Aim. Study the functional properties of cationic antimicrobial peptides 0-defensins isolated from baboon Papio hamadryas blood leukocytes. Materials and methods. Baboon 0-defensins were extracted from leukocyte mass using ultrafiltration, preparative electrophoresis and reverse phase high performance liquid chromatography. The test microorganisms used were Gram-negative bacteria Escherichia coli, Gram-positive bacteria Listeria monocytogenes and Staphylococcus aureus, and fungi Candida albicans. Minimal inhibitory concentrations (MICs) were determined by testing serial dilutions of the test peptides by radial diffusion in agarose gel. Microbicidal action was evaluated by counting surviving colony forming units after incubation microorganisms with the peptides. The 0-defensins influence on E.coli membrane permeability was assessed using chromogenic markers o-nirofenil- β-D-galactopyranoside and nitrocefin. Results. The analysis of the 0-defensins antimicrobial properties showed that they produce antimicrobial activity against test microorganisms, exhibiting bactericidal and fungicidal effects at micromolar concentrations. We studied the influence of different environmental conditions (low and high ionic strength, blood serum in medium) for antimicrobial activity. It is shown that 0-defensins have the ability to increase the outer membran of E.coli permeability, however, in contrast to 0-defensins have no noticeable influence on the inner membrane permeability. Conclusion. Baboon 0-defensins isolated from blood leukocytes are effective antimicrobial agents with a broad spectrum of microbicidal action. 0-Defensins baboon unlike 0-defensins exhibit antimicrobial activity in environments with high ionic strength. 0-Defensins increase the outer membran of E.coli permeability but not the cytoplasmic membrane, suggesting that the mechanism of antimicrobial effect of these peptides other than 0-defensins.