This study examined whether adding levofloxacin to a standard four-drug regimen improved the 8-week culture response and compared effectiveness of 9 versus 6 months of intermittent therapy for human immunodeficiency virus-related pansusceptible pulmonary tuberculosis. Patients were randomized to receive either four or five drugs, the fifth being levofloxacin. Patients who completed induction therapy were randomized to complete 9 versus 6 months of intermittent therapy with isoniazid and rifampin. In the randomized induction phase, 97.3% of patients in the four-drug group and 95.8% in the five-drug group had sputum culture conversion at 8 weeks (P = 1.00). In the continuation phase, one patient (2%) assigned to 9 months and two patients (3.9%) assigned to 6 months of therapy had treatment failure/relapse (P = 1.00). In conclusion, this study showed that levofloxacin added no benefit to a highly effective, largely intermittent, four-drug induction regimen. Both 9 and 6 months of intermittent therapy were associated with low treatment failure/relapse rates.