Clinical and Laboratory Standards Institute (CLSI) broth dilution reference methods are available for susceptibility testing of yeasts (see CLSI document M27--Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts) and moulds (see CLSI document M38--Reference Method for Broth Dilution Antifungal Susceptibility Testing of Filamentous Fungi). There still remains, however, a need for an alternative simple, rapid, and cost-effective approach to determine susceptibility of fungal organisms to various classes of antifungal agents that would make antifungal susceptibility testing more readily available to the clinical microbiology laboratory. The CLSI Subcommittee on Antifungal Susceptibility Testing has therefore developed a disk diffusion method for testing yeasts. CLSI document M44-A2--Method for Antifungal Disk Diffusion Susceptibility Testing of Yeasts; Approved Guideline--Second Edition provides approved zone interpretive criteria (breakpoints) for Candida species for caspofungin, fluconazole, and voriconazole after 20 to 24 hours incubation, as well as quality control parameters for caspofungin, fluconazole, posaconazole, and voriconazole. There are currently more than 10 systemically active antifungal agents, and it is expected that this document will further encourage the development of disk diffusion testing for at least some of these additional agents and genera.