Ascosphaera apis is one of the major fungal pathogens of honey bee broods and the causative agent of Chalkbrood disease. The factors responsible for the pathogenesis of Chalkbrood disease are still not fully understood, and the increasing resistance of A. apisto commonly used antifungal agents necessitates a search for new agents to control this disease. The in vitro antifungal activities of 27 plant essential oils against two isolates ofA. apis (Aksu-4 and Aksu-9) were evaluated.