Avian favus (dermatophytosis) is a superficial mycosis caused by Microsporum gallinae in poultry. This disease is an important problem in poultry husbandry, but the standard antifungal treatment can leave drug residues in farm products. The aim of this study was to compare the efficacy of a clove essential oil ointment (3%, w/w) with commercially available ketoconazole cream (2%, w/w) for the treatment of M. gallinae infection in chickens. An in vitro time-kill assay showed that clove essential oil ointment reduced the number of viable M. gallinae ATCC 90749 by 99.99% within 1 hr. A randomized controlled trial showed that the therapeutic efficacy of clove essential oil ointment (3%, w/w) was noninferior to ketoconazole cream (2%, w/w) in M. gallinae–infected chickens. The percentage of completely recovered (culture-negative) animals in both treatment groups was 90% in day 35 after initial treatment. This study indicates that clove essential oil is suitable for preparation as an alternative topical treatment for avian dermatophytosis.