Clinical and Laboratory Standards Institute document M27-A3--Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts; Approved Standard--Third Edition describes a method for testing the susceptibility of antifungal agents to yeast that cause invasive fungal infections, including Candida spp. (and Candida glabrata), and Cryptococcus neoformans. Selection and preparation of antifungal agents, implementation and interpretation of test procedures, and the purpose and implementation of quality control procedures are discussed. A careful examination of the responsibilities of the manufacturer and the user in quality control is also presented.