We conducted a prospective study to address the prevalence and microbiological characteristics of yeast isolates colonizing the oral cavities of HIV-infected patients undergoing highly active antiretroviral therapy. Sixty-eight patients (67%) from a total of 102 were found to be colonized with yeasts. Sixty-five patients carried a single species (60 Candida albicans, three Candida glabrata and two Candida krusei) and three patients had mixed colonization of C. albicans and C. krusei. The status of yeast carrier was not associated with the number of CD4 cells or the viral load. Similarly, the type of antiretroviral regimen was not associated with the carriage of Candida spp. The only predictor of Candida colonization was a previous history of oropharyngeal candidiasis (P = 0.009). Although many patients in this series had already been treated with repeated courses of fluconazole therapy for previous episodes of oropharyngeal candidiasis, fluconazole susceptibility patterns showed that 93% of yeasts were susceptible to this triazole in vitro (MIC < or = 8.0 mg/L).