In an effort to update and clarify policies on tuberculosis drug susceptibility testing (DST), the World Health Organization (WHO) commissioned a systematic review evaluating WHO-endorsed diagnostic tests. We report the results of this systematic review and meta-analysis of the diagnostic accuracy and reproducibility of phenotypic DST for first-line and second-line antituberculosis drugs. This review provides support for recommended critical concentrations for isoniazid and rifampin in commercial broth-based systems. Further studies are needed to evaluate critical concentrations for ethambutol and streptomycin that accurately detect susceptibility to these drugs. Evidence is limited on the performance of DST for pyrazinamide and second-line drugs.