The efficacy of anidulafungin, an echinocandin antifungal agent with potent anti-Candida activity, in treating esophageal candidiasis was tested in a double-blind study versus oral fluconazole. Isolates were identified and tested for susceptibility. Candida albicans represented >90% of baseline isolates. The MIC(90) of anidulafungin for all strains was 0.06 mg/liter.