Coccidioidomycosis is a systemic infection caused by the soil-dwelling dimorphic fungi Coccidioides spp. The disease is endemic in semiarid Northeast Brazil, where it is caused by C. posadasii. The aim of this study was to perform antifungal susceptibility tests of clinical and environmental strains of C. posadasii from Northeast Brazil. The in vitro activities of caspofungin, amphotericin B and azoles against clinical and environment isolates of C. posadasii were determined in accordance with the NCLLS M-38P macrodilution method. The antifungal susceptibility analysis showed that all the strains of C. posadasii (n = 10) were sensitive to caspofungin (16 microg/ml < or = MIC < or = 32 microg/ml), amphotericin B (0.0625 mug/ml < or = MIC < or = 0.125 microg/ml), ketoconazole (0.039 microg/ml < or = MIC < or = 0.156 microg/ml), itraconazole (0.125 microg/ml < or = MIC < or = 0.5 microg/ml), fluconazole (3.125 microg/ml < or = MIC < or = 6.25 microg/ml), and voriconazole (0.125 microg/ml). This study is the first description of in vitro antifungal susceptibility pattern of Brazilian strains of C. posadasii.