Urinary tract infections (UTIs) are widespread in Russia. One of the major problems facing practical medicine in the country is laboratory diagnosis of pyoinflammatory diseases of the urogenital tract caused by opportunistic microorganisms. A major difficulty in this context is posed by polyresistance of certain Gram-negative bacteria (E.coli, Klebsiella spp., etc.) associated with their production of a great variety of beta-lactamases (BL). This study was designed to determine species composition of urogenital tract pathogens and evaluate their resistance to antibacterial preparations with special reference to the mechanism of resistance of BL production to this drugs. The study included 169 patients with urinary tract infections admitted to the Clinical Research Centre for Healthcare of Miners, Leninsk-Kuznetsk, between 01.02.2007 and 0.1.02.2008