A total of 656 female patients from Russia aged between 18 to 65 years with uncomplicated cystitis entered the international ARESC trial, of them 647 were eligible for final analysis. Positive cultural urine tests ( > 10(4) CFU/ml) were in 419 (64.7%) patients, 393 (93.8%) patients had monoinfection. The central laboratory of Genoa (to which the isolated samples were sent) has tested 416 uropathogens from 399 patients. The following pathogens were isolated: E. coli (72.6%), enterococcus (7.0%), Klebsiella pneumoniae (4.6%), Staphylococcus saprophyticus (3.6%), Proteus mirabilis (2.4%) and Staphylococcus aureus (1.7%). E. coli was most sensitive to phosphomycin (99.3%), mecillinam (97.3%), nitrofurantoin (94.7%), ciprofloxacin (87.4%). The lowest sensitivity was to ampicillin (42.1%) and cotrimoxasol (69.4%). As to the whole bacterial spectrum, the highest sensitivity was found to phosphomycin (96.5%), nitrofurantoin (85.6%) and citrofloxacin (82.8%), the less sensitivity--to ampicyllin (44.3%) and co-trimoxasol (70.1%). Phosphomycin, mecillinam (not registered in Russia) and nitrofurantoin showed activity in vitro and can be considered as drugs of choice for empiric therapy of cystitis. Because of high resistance of pathogens, co-trimoxasol (trimetoprim) and fluoroquinalones are not recommended as first-line treatment for uncomplicated cystitis in females.