Fluconazole has proved to be effective in treating oropharyngeal and esophageal candidiasis in immunocompromised patients. However, sufficient data are lacking regarding the efficacy of this agent in neutropenic hosts. The aim of the present study was to determine the clinical and mycological efficacy of fluconazole and to define the factor(s) affecting the outcome of fluconazole therapy in severely neutropenic patients (peripheral neutrophil count, < 500/microL) with cancer who have oropharyngeal and/or esophageal candidiasis. One hundred eleven patients with 129 episodes of candidal infections were treated with intravenous and consequently oral fluconazole (200 mg/d and 100 mg/d, respectively). Overall clinical cure and mycological eradication rates were 82% and 56%, respectively. Persistent neutropenia (P < .01), infection with a non-albicans strain of Candida (P = .012), and administration of antifungal therapy during the second or a later neutropenic episode (P < .002) were independently associated with a worse outcome. We conclude that fluconazole is effective in the treatment of upper gastrointestinal candidiasis in neutropenic patients with cancer. Effective treatment of the underlying malignancy, with the resultant recovery from neutropenia, and the determination of the species of infecting Candida isolates are required for the prediction of the outcome of antifungal therapy.