Introduction: Currently, developing new antibacterial drugs as alternative antibiotics is a very active area of research, due to widspreading widespread prevalence of resistant strains of microorganisms. This work intends to investigate of antibacterial properties and influence on immune blood cells of the silver-based compound hexamethylenetetramine (methenamine) silver nitrate with general formula [Ag(CH2)6 N4]NO3. Materials and Methods: The antibacterial effect of the silver complex was investigated by agar diffusion and serial dilution methods. Silver complex have been investigated for its impact on the phagocytic activity of neutrophils and on immune cells during the reaction of blast transformation of lymphocytes (RBTL). Results: Studies have shown that hexamethylenetetramine silver nitrate possesses both bactericidal and bacteriostatic dose-dependent effect on tested bacterial strains, including Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa, Streptococcus pneumoniae. Escherichia coli were shown to be the most susceptible bacteria. Cytotoxic effect of silver salt on lymphocytes was detected in high dosage in RBTL. No significant immunosuppressive impact on neutrophils phagocytic activity of tested complex was shown. Conclusion: Agents of nosocomial infections were highly susceptible to the drug. Complex has proved to be promising as a prospective antibacterial drug with wide range of activity.