PA-824 is a promising drug candidate for the treatment of tuberculosis (TB). It is in phase II clinical trials as part of the first newly designed regimen containing multiple novel antituberculosis drugs (PA-824 in combination with moxifloxacin and pyrazinamide). However, given that the genes involved in resistance against PA-824 are not fully conserved in theMycobacterium tuberculosiscomplex (MTBC), this regimen might not be equally effective against different MTBC genotypes. To investigate this question, we sequenced two PA-824 resistance genes (fgd1[Rv0407] andddn[Rv3547]) in 65 MTBC strains representing major phylogenetic lineages. The MICs of representative strains were determined using the modified proportion method in the Bactec MGIT 960 system. Our analysis revealed single-nucleotide polymorphisms in both genes that were specific either for several genotypes or for individual strains, yet none of these mutations significantly affected the PA-824 MICs (≤0.25 μg/ml). These results were supported byin silicomodeling of the mutations identified in Fgd1. In contrast, “Mycobacterium canettii” strains displayed a higher MIC of 8 μg/ml. In conclusion, we found a large genetic diversity in PA-824 resistance genes that did not lead to elevated PA-824 MICs. In contrast,M. canettiistrains had MICs that were above the plasma concentrations of PA-824 documented so far in clinical trials. AsM. canettiiis also intrinsically resistant against pyrazinamide, new regimens containing PA-824 and pyrazinamide might not be effective in treatingM. canettiiinfections. This finding has implications for the design of multiple ongoing clinical trials.