SummaryTwenty‐seven patients with various dermatophyte infections took part in a double blind study. Thirteen patients were given ketoconazole 200 mg daily and 14 griseofulvin 500 mg daily for up to 60 days. Following ketoconazole therapy, 12 of 13 patients were healed, with minimal lesions in one. In the griseofulvin‐treated group ten of 14 were healed, three having minimal residual lesions and one was a treatment failure. There was a tendency for T. rubrum infections to respond more completely to ketoconazole treatment. At six‐month follow up there was one griseofulvin‐treated failure and one relapse while there were three ketoconazole relapses.It is concluded that both ketoconazole and griseofulvin are effective in treating dermatophyte infections and ketoconazole is a safe alternative to griseofulvin if intolerance or allergy to griseofulvin