The objective was to determine the oral carriage patterns of yeasts and coliforms and their relationships, if any, with age, risk group, CDC classification, CD4+ count and medications in a predominantly Chinese, HIV-infected cohort in Hong Kong. A prospective longitudinal study was carried out over a 12-month period, of 32 predominantly Chinese male HIV-infected cohort in a hospital setting in Hong Kong. Oral carriage rates were determined by the concentrated rinse culture method and correlated with other clinical parameters using regression analysis. A total of 73 oral rinse samples were collected and the weighted mean carriage rates of oral yeasts and coliforms were 54.8% and 28.8%, respectively. The most common yeast and the Enterobacteriaceae isolated were Candida albicans and Enterobacter cloacae, respectively. An increased carriage rate of yeasts was associated with zidovudine usage and Centres for Disease Control (CDC) stage IV of the HIV infection whereas the opposite was associated with the usage of antiparasitics and multivitamins. Although the oral carriage rate of coliforms was significantly lower in individuals taking antibacterials and multivitamins, it was not significantly influenced by age, CD4+ lymphocyte count and the intake of antivirals, antifungals or folates. These data imply that oral yeast carriage in HIV infection is related to the severity of the disease as opposed to oral coliform carriage which appears to be unusually transient in the study cohort.