In our study 77 AIDS patients suffering from oral and/or esophageal candidiasis were evaluated: 38 received fluconazole, 39 ketoconazole. We analyzed the rates of clinical and mycological responses, relapses and toxicities. In vitro susceptibility tests for both antifungal drugs were performed by evaluating their Minimal Inhibitory Concentrations (MICs). The azole drugs investigated show a good activity in the treatment of oropharyngeal and esophageal candidiasis also in advanced stages of HIV infection. Clinical cure or improvement were achieved in 29 (76.3%) and 31 (79.4%) of the patients treated with fluconazole or ketoconazole respectively. Clinical or laboratory adverse experiences related to fluconazole were seen in 7 (21.2%) patients while ketoconazole provoked adverse experiences in 9 (26.4%) patients. In vitro susceptibility tests, if repeated more than once, both in primary infection and relapses, could be important to demonstrate a probable sensitivity change or resistance of the tested strains.