Cryptococcus gattii is an emerging agent of cryptococcosis that is indistinguishable from Cryptococcus neoformans by most routine laboratory tests, e.g., cryptococcal antigen test, commercial biochemical identification systems for yeast, microscopic morphology, etc. C. gattii infects both immuno-competent and immuno-compromised individuals, and may be associated with worse clinical outcomes. Due to increasing awareness of C. gattii infections, laboratories may be asked to distinguish C. gattii from C. neoformans. C. gattii can only be differentiated from C. neoformans by specific biochemical or molecular testing. This guidance document assists in identifying it.