A prospective epidemiological study of the spectrum of causative agents (CA) of uncomplicated urinary tract infections (UTI) in adult patients and CA resistance to antimicrobial drugs was conducted in nine cities of the Russian Federation in 2004-2005. Minimum inhibiting concentrations were ascertained by dilution in agar according to NCCLS (2000-2002) recommendations. The study has found that uncomplicated UTI are most frequently caused by E.coli (73.9%). Other CA occur much less frequently: K.pneumoniae--6.4%, E. faecalis--4.4%, S. epidermidis--4.1%, Staphylococcus spp--3.4%, others--2% patients. E. coli demonstrated high resistance to ampicilline (33.1%), co-trimoxasol (19.4%). Most active against E. coli were fluoroquinolones (norfloxacin, ciprofloxacin, levofloxacine), the resistance being 4.8%; cefalosporins of the second and third generation (cefuroxim, ceftibuten), nitrofurantoin, no resistant strains were found.