Ovalicin, a secondary metabolite produced by an entomopathogenic fungus Metarhizium anisopliae var. anisopliae, is currently used as an efficient biological control agent against various agricultural insect pests, but not so many biological activities have been investigated. To assess whether ovalicin has potential in ameliorating atopic dermatitis-related symptoms in mice, we first sensitized skin in the dorsal neck of Balb/c mice using compound 48/80, and scrutinized whether the compound affected the atopic dermatitis-related symptoms. The results revealed that ovalicin significantly reduces scratching behavior in a concentration-dependent fashion. Moreover, the treatment inhibits the levels of the degranulation of mast cells by 65%, and levels of histamine release by 51% at a concentration of 10 µg/ml. Together, the present data strongly suggest that ovalicin elicits potential anti-atopic activities in mice.