Caspofungin is a new broad-spectrum antifungal drug. A multicenter, double-blind, randomized trial was conducted to assess the efficacy, safety, and tolerability of caspofungin relative to amphotericin B in adults with endoscopically documented symptomatic Candida esophagitis. By use of a modified intent-to-treat analysis, endoscopically verified clinical success was achieved in 74% (95% confidence interval [CI], 59%-86%) and 89% (95% CI, 72%-98%) of patients receiving caspofungin at 50 and 70 mg/day, respectively, and in 63% (95% CI, 49%-76%) of patients given amphotericin B at 0.5 mg/kg/day. Therapy was stopped because of drug-related adverse events in 24% of patients in the amphotericin B group and 4% and 7%, respectively, for the caspofungin groups. This report provides the first demonstration of clinical utility for an echinocandin compound. Caspofungin appeared in this study to be as effective as and better tolerated than amphotericin B for the treatment of esophageal candidiasis.