Antifungal drug resistance is a growing problem in HIV positive and AIDS patients.  Resistance may be related to antifungal agents used for the treatment of patients with candidiasis. This study investigated the effect of previous exposure to antifungal agents on the carrier rate of yeasts in HIV positive subjects.  A total of 247 patients attending the HIV clinic at the New Johannesburg Hospital, Gauteng were investigated. At the time of sampling none of the patients had evidence of oral lesions. Whole unstimulated saliva samples were collected by expectoration for 10 minutes.  The samples were cultured for the presence of yeasts on Sabouraud Dextrose agar and incubated at 37degrees C for 48 hours.  The number of colony forming units (cfu) of yeasts per ml of saliva was counted and isolates were identified using colonial morphology and Gram stain characteristics.  A record of previous antifungal treatment was obtained from the hospital records of the patients. Seventy two patients did not receive antifungal therapy whereas 175 had been treated with antifungal agents previously.  The patients were subdivided further into 2 groups, those that carried less than 1,500 colony forming units (cfu) per ml of saliva and those carrying more than 1,500. The data were analysed using the ÷2 test, which showed that 118 (67.5%) patients who had not received antifungal therapy previously carried less than 1,500 yeasts in their saliva.  In contrast only 33 (45.7%) patients who had received therapy carried less than 1,500 yeasts per ml of saliva (p < 0.000046). There were no significant differences between patients who carried > 1,500 cfu per ml of saliva.  Exposure to antifungal agents in HIV positive patients significantly reduced the number of patients with low yeast counts and may predispose patients to the development of candidiasis.   Supported by 3M Pharmaceuticals South Africa (Pty) Ltd and Colgate-Palmolive (Pty) Ltd.