In an open study, twenty-eight patients with toenail onychomycosis were treated with monthly cycles of 400 mg itraconazole daily for one week for three (n = 5) or four (n = 23) consecutive months. In this patient sample, a total of seventy-one toenails were affected, with a mean nail-plate involvement of 55 percent (range, 20 to 100 percent). Trichophyton rubrum was the most frequently isolated pathogen, followed by T. mentagrophytes. After active therapy, patients were evaluated for a maximum period of two years (mean, twelve months). A total of twenty-six of twenty-eight patients (93 percent) were considered as clinically cured. Of the remaining two patients, one was markedly improved and one appeared to have relapsed. Only three of seventy-one nails still exhibited some pathologic involvement. Of the twenty-six patients considered cured, mycologic examination at the final visit was performed on thirteen and the results were negative in all of them. The remaining clinically cured patients had no mycologic examination at the last visit. This short treatment was well tolerated; the only adverse reaction being a mild headache in one patient. Patients preferred this regimen to receiving daily treatment for three months. Pulse therapy consisting of monthly one-week cycles of 400 mg itraconazole daily for three to four months may offer a new option for treatment of onychomycosis. Further large-scale studies are required to confirm these findings.