||Rapid amphibian extinctions and declines have been occurring worldwide over the past few decades, often in areas of limited human impact. 1,2,3 These massive declines have been linked to the deadly fungal pathogen Batrachochytrium dendrobatidis ( Bd ), the causative agent of chytridiomycosis. 4,5,6,7 Interestingly, a range of tolerances to Bd have been observed; where some populations have declined, others have not declined or have recovered. 20 Several factors account for variations in susceptibility of different individuals to Bd infection, such as environmental conditions, immune responses of the individual, and presence of symbiotic cutaneous antifungal bacteria. 4,7,9,21,22,23 This report details an investigation of the chemicals produced by these cutaneous antifungal bacteria that mediate this deadly disease.