Saline oral rinse samples were obtained from 300 community-dwelling Hong Kong Chinese attending an outpatient dental clinic to determine the oral prevalence of aerobic and facultatively anaerobic Gram-negative rods (AGNR) and yeasts. The oral prevalence of AGNR was 41.7%. Enterobacteriaceae species comprised 73% of all AGNR isolated, with an overall prevalence of 32%. There was no difference in prevalence between females (n = 190) and males (n = 110). Morning samples (n = 154) yielded a significantly higher prevalence of AGNR (54.5%) and Enterobacteriaceae (42.2%) than afternoon samples (n = 146) (28.1 and 21.2%, respectively; p < 0.01, p < 0.01). Subjects over 50 yr had a significantly higher prevalence of AGNR than those aged 30-49 yr (p < 0.01). The most commonly isolated AGNR species were Enterobacter cloacae and Klebsiella pneumoniae pneumoniae. The oral prevalence of yeasts was 24%, with Candida albicans forming 77% of all yeasts isolated. Subjects taking medication (n = 38) or wearing dentures (n = 38) had a significantly higher oral yeast prevalence of 36.8 (p < 0.05) and 44.7% (p < 0.01), respectively. Yeast prevalence was significantly higher in subjects over 50 yr than those aged 30-49 yr (p < 0.05) and 15-29 yr (p < 0.05). Comparisons with previous studies suggest that the oral prevalence of AGNR in Chinese may be higher in Hong Kong than in other parts of the world.