Eighty-eight immunocompetent patients with deep mycoses from eight countries were evaluated with the same protocol for efficacy of fluconazole monotherapy. Entry doses were raised from 100 to 400 mg as safety was shown in initial cohorts, and dosages up to 2,400 mg daily and durations up to 44 months were studied. Results were very similar in different countries. Twenty-seven of 28 evaluable patients with paracoccidioidomycosis, 13 of 19 with sporotrichosis, 14 of 16 with coccidioidomycosis, and eight of eight with histoplasmosis demonstrated objective responses to therapy, as did one patient each with zygomycosis and alternariosis. For these patients, relapses have been unusual thus far. In contrast, one patient with chromoblastomycosis responded but relapsed, and six did not respond; one patient with mycetoma responded but relapsed, and two did not respond. The drug was well tolerated by patients, including six who received intravenous therapy. In vitro susceptibility tests suggested that clinical response was correlated with susceptibility but that resistance did not preclude clinical response. Fluconazole therapy appears efficacious for several deep mycoses; dosages of >200 mg daily may be needed for some diseases. The further evaluation of fluconazole for these entities is warranted.