We were intrigued by Zaias and Rebell's1 recent report of long-term, intermittent dosing of itraconazole and terbinafine for the treatment of onychomycosis. We concur that the pharmacodynamic incorporation of antifungal medication into the nail bed is not well understood. We are particularly interested in the effectiveness of intermittent treatment with terbinafine. Terbinafine is a fungicidal medication, which, when administered at standard dosages (250 mg/d), rapidly penetrates and accumulates in the nail, where it remains at therapeutic levels for up to 9 months.2 The results of 4 trials, including that of Zaias and Rebell,1,3-5 suggest that intermittent dosing of terbinafine may be effective for the treatment of onychomycosis, possibly reducing medication costs and drug exposure.