We compared the in vitro activities of isavuconazole, posaconazole, voriconazole, and fluconazole against Dipodascus capitatus (n = 21), Saccharomyces cerevisiae (n = 20), Rhodotorula mucilaginosa (n = 18), and Trichosporon spp. (n = 15). The MIC(50)s, MIC(90)s, and MIC ranges (in microg/ml) obtained using the CLSI M27-A3 procedure were as follows: isavuconazole, 0.125, 0.5, and < or = 0.015 to 2; posaconazole, 0.5, 2, and < or = 0.015 to > 16; voriconazole, 0.125, 2, and < or = 0.015 to 8; and fluconazole, 4, > 128, and < or = 0.125 to > 128. Isavuconazole showed potent activity against the isolates studied.