A total of 62 patients with HIV-related conditions were examined for clinical and mycological oral findings, Cultures from 51 patients were positive for yeasts and included 49 Candida albicans and 8 non-albicans isolates, Of patients with positive culture, 35% had pseudomembraneous thrush, Tn vitro susceptibility testing of 49 C, albicans isolates revealed that the minimal inhibitory concentration for 50% of the strains (MIC(50)) was 2.0 mg/l for fluconazole, and the MIC(50) was less than or equal to 0.125 mg/l for both ketoconazole and itraconazole. Fluconazole resistance (MIC greater than or equal to 32.0 mg/l) was found for 14% of the C. albicans isolates tested. Two C. albicans isolates showed cross-resistance to ketoconazole and itraconazole. Associations between reduced susceptibility to fluconazole and low CD4+ cell counts, the length of time since the first AIDS-defining illness and the interval from the first fluconazole treatment, indirectly reflecting the total fluconazole exposure, were observed,