The antibiotic susceptibilities of 59 Enterobacter cloacae and 39 Klebsiella pneumoniae human oral isolates collected from a southern Chinese population in Hong Kong were investigated for their susceptibility to eight antibiotics: ampicillin, cephalothin, cefuroxime, ceftazidime, ciprofloxacin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole using the E-Test method for direct quantification of minimum inhibitory concentrations. Most strains were sensitive to all antibiotics except ampicillin and cephalothin. Ampicillin resistance was exhibited by 82% of K. pneumoniae and 69% of E. cloacae isolates. Eighty-eight percent of E. cloacae isolates were resistant to cephalothin. Several strains fell within the intermediate category of sensitivity for ampicillin (E. cloacae and K. pneumoniae), cefuroxime (E. cloacae) and tetracycline (K. pneumoniae). Comparison with other Hong Kong data suggests that resistance rates to cefuroxime, ceftazidime, ciprofloxacin, gentamicin, tetracycline and trimethoprim/sulfamethoxazole exhibited by the oral isolates are generally lower than in enterobacters and Klebsiella spp. isolated from urine, skin and soft tissues in Hong Kong populations.