We studied the activity of voriconazole against 400 clinical strains of Aspergillus from the pre-voriconazole (1999 to 2002) and post-voriconazole (2003 to 2007) periods. Although the mean MICs of strains from the post-voriconazole period were slightly higher (0.39 versus 0.57 microg/ml; P < 0.001), all strains were susceptible to voriconazole and presented an MIC of