Seven Bennett's wallabies (Macropus rufogriseus rufogriseus) presented within a period of several months with onychodystrophy, onychomadesis, and severe digital tumefaction. Histopathologic findings included a pseudocarcinomatous hyperplasia of the claw matrix surrounding a cavity filled with keratin and septate hyphae stained with periodic acid Schiff reagent. The fungal species Chrysosporium keratinophilum was identified on cultures. The wallabies were orally treated with ketoconazole (15 mg/kg s.i.d.) for 20 wk. Material and enclosures were cleaned and sprayed with 0.2% enilconazole solution once a month over a period of 4 mo. No improvement of advanced cases was observed, but no new case appeared for the next 6 mo. The positive mycological culture and the invasion of tissues on histopathologic examination suggested that the fungal species C. keratinophilum was implicated in this claw disease. This is the first report of onychomycosis caused by C. keratinophilum in animals.