Primers to amplify the genes encoding the virulence factors of uropathogenic Escherichia coli, such as pilus associated with pyelonephritis (pap), haemolysin (hly), aerobactin (aer) and cytotoxic necrotizing factor 1 (cnf1) genes, were designed. The above primers along with previously reported primers for S fimbriae (sfa) and afimbrial adhesin I (afaI) genes were combined to develop a multiplex polymerase chain reaction (PCR) for detection of the respective virulence factors and for the identification of uropathogenic E. coli. The multiplex PCR to detect pap, sfa, afaI, hly, aer and cnf1 genes was highly specific and the sensitivity was found to be about 5 x 10(3) colony forming units of E. coli per ml. A total of 194 E. coli strains isolated from patients with simple acute cystitis were examined by the multiplex PCR and the results were in complete agreement with that obtained by DNA colony hybridization test. The multiplex PCR developed was, therefore, concluded to be a useful, sensitive and rapid assay system to identify uropathogenic E. coli.