Three multicenter, randomized, double-blind, placebo-controlled studies were conducted to determine whether twelve weeks of therapy with itraconazole, 200 mg, was effective in the treatment of dermatophyte infection of the toenail. Significantly more patients treated with itraconazole (110 patients) than with placebo (104 patients) achieved clinical (65 percent vs. 3 percent) and mycologic (54 percent vs. 6 percent) success. The mean percentage of affected reference nail before the initiation of therapy was 76 percent. Adverse events were comparable in the two treatment groups. These findings demonstrate that twelve weeks of continuous itraconazole, 200 mg once daily, is a highly effective, well-tolerated therapy for the management of toenail onychomycosis.