ABSTRACTThe MICs and minimum fungicidal concentrations (MFCs) of amphotericin B, miconazole, itraconazole, ketoconazole, fluconazole, and flucytosine for 52 isolates ofPaecilomycesspecies were evaluated by the broth microdilution method, largely based on the recommendations of the National Committee for Clinical Laboratory Standards (document M27-A). The fungal isolates tested included 16P. variotii, 11P. lilacinus, 9P. marquandii, 6P. fumosoroseus, 4P. javanicus, and 2P. viridisisolates and 1 isolate of each of the following species:P. carneus,P. farinosus,P. fulvus, andP. niveus. The MFCs and the MICs at which 90% of isolates were inhibited (MIC90s) for the six antifungal agents were remarkably high; the MIC50s indicated that amphotericin B, miconazole, itraconazole, and ketoconazole had good activities, while fluconazole and flucytosine demonstrated poor efficacy. The ranges of the MICs were generally wider and lower than those of the MFCs. There were significant susceptibility differences among the species. All species with the exception ofP. variotiiwere highly resistant to fluconazole and flucytosine;P. variotiiwas susceptible to flucytosine. Amphotericin B and the rest of the azoles showed good activity againstP. variotii, while all the antifungal agents assayed showed low efficacy againstP. lilacinus.