The primary objective of this Phase II clinical trial is to compare the safety and microbiological activity of a moxifloxacin-containing regimen (isoniazid, rifampin, pyrazinamide, moxifloxacin [HRZMoxi]) to a control regimen (isoniazid, rifampin, pyrazinamide, ethambutol [HRZE]) in the first two months of treatment of sputum smear-positive pulmonary tuberculosis. In addition, the study will evaluate whether intermittent administration (thrice-weekly after the first 2 weeks) of these regimens affects their tolerability and microbiological activity. The assessment of microbiological activity will be sputum culture-conversion. Improved sputum culture conversion after 2 months of treatment with a moxifloxacin-containing regimen would support phase 3 clinical trials of moxifloxacin in treatment regimens of less than the current 6 month standard regimens.