Fluconazole therapy was evaluated prospec-tively in 108 patients with immunossupression and serious fungal infections. Patients were enrolled if they had a life-threatening fungal infection and conventional therapy had failed to eradicate infection, had caused serious toxic reactions, or was contraindicated. Patients were treated with 50 to over 400 mg/day initially. AIDS was underlying risk factor in 66.6% of the patients evaluated in the study and in 92.9% of 57 patients with cryptococcal infection. Satisfactory clinical response was observed in 43 patients with active cryptococcal infection and in 39 patients with active candidiasis, 90.7% and 92.3% respectively. Concerning mycologic response, 63.3% and 80.7% of 30 patients with cryptococcal infection and 26 patients with candidiasis respectively had final negative cultures. Eleven patients (10.2%) had adverses effects possibly due to fluconazole therapy. Fluconazole may be effective in the treatment of cryptococcal infection and candidiasis and can be an alternative to conventional antifungal therapy.