Tuberculosis (TB) program, Damien Foundation Projects, Bangladesh. To summarize the outcome and its determinants of the first treatment for multidrug-resistant TB using a standardized regimen consisting of a minimum 9 months. This was a prospective, observational study of a gatifloxacin (GFX) based directly observed regimen, mainly with initial hospitalization. The 4-month intensive phase was extended until sputum smear conversion. Patients were monitored using culture for up to 2 years after treatment completion. Of the 515 patients who met the study inclusion criteria and were successively enrolled from 2005 to 2011, 84.4% had a bacteriologically favorable outcome. Due to extensive disease with delayed sputum conversion, only half of the patients completed treatment within 9 months; however, 95% were able to complete treatment within 12 months. Eleven patients failed or relapsed, and 93.1% of the 435 patients who were successfully treated completed at least 12 months post-treatment follow-up. The strongest risk factor for a bacteriologically unfavorable outcome was high-level fluoroquinolone (FQ) resistance, particularly when compounded by initial pyrazinamide (PZA) resistance. Low-level FQ resistance had no unfavorable effect on treatment outcome. Amplification of drug resistance occurred only once, in a patient strain that was initially only susceptible to kanamycin and clofazimine. The excellent outcome of the Bangladesh regimen was largely maintained. Bacteriological treatment failures and relapses were rare, except among patients with high-level GFX resistance, notably in the presence of PZA resistance.