Shortened antituberculosis treatment regimens are expected to improve patient adherence to treatment, thus favoring better case management and disease control and minimizing the risk of drug resistance.1-3 The first indication that fluoroquinolones had the potential to shorten tuberculosis treatment was from an observational study in India4 in which ethambutol was replaced with ofloxacin. The fourth-generation fluoroquinolones gatifloxacin and moxifloxacin have shown mycobactericidal activity that is better than that of ofloxacin in vitro5 and in vivo,6-9 and these agents have the potential to shorten treatment. Gatifloxacin was chosen for this study on the basis of its bactericidal-activity profile, cost, and generic status. We conducted a phase 3 trial that evaluated the efficacy and safety of a 4-month gatifloxacin-containing regimen, as compared with a standard 6-month regimen, for the treatment of rifampin-sensitive pulmonary tuberculosis.