A protocol for determining the antifungal efficacy of systemic or topical drugs in tinea pedis is presented. In this study, (1) no patient had concomitant onychomycosis; (2) the clinical types were separated into (a) plantar scaling, (b) intertriginous, and (c) vesicular instep; (3) the soles were treated for three months (time related to the shedding of all stratum corneum); (4) the follow-up period for soles was three months (related to characteristics of the drug and its depot effect on the target area, the horny layer); (5) the final evaluation related to the percentage of patients "clinically and mycologically cured" at the end of the follow-up period. With this protocol, ultramicrosize griseofulvin (Gris-PEG) alone, topical clotrimazole (Lotrimin) alone, and a combination of the two were tested in seventy-three patients with tinea pedis. The results were as follows: for plantar scaling type of tinea pedis, the combination was not better than griseofulvin alone; for intertriginous tinea pedis, the combination was definitely better than griseofulvin alone; and topical 1 percent clotrimazole was much less effective than griseofulvin.