The aim of this study is to evaluate the treatment outcomes and identify factors associated with adverse tuberculosis treatment outcomes for bacteriologically confirmed pulmonary tuberculosis. Treatment outcomes of pulmonary tuberculosis were evaluated retrospectively among 11,186 smear- and/or culture-positive patients treated between 2006 and 2009 in Istanbul, Turkey. Adverse treatment outcomes were identified in 1,010 (9.0%) patients including death (1.8%), treatment default (6.1%), and treatment failure (1.1%). Factors associated with adverse treatment outcomes included being born abroad (odds ratios [OR], 5.38; 95% confidence intervals [CI], 3.67-7.91), history of tuberculosis treatment (OR, 3.77; 95% CI, 3.26-4.36), age > 65 years (OR, 2.79; 95% CI, 2.21-3.53), and male gender (OR, 1.91; 95% CI, 1.59-2.27). Death was most strongly associated with age > 65 years (OR, 45.1; 95% CI, 27.0-75.6), followed by treatment default with history of interrupted treatment (OR, 11.6; 95% CI, 8.94-15.1), and treatment failure with prior history of treatment failure (OR, 17.1; 95% CI, 6.97-41.6). Multidrug resistance was strongly associated with adverse treatment outcomes (OR, 10.8; 95% CI, 8.02-14.6). Age > 65 years, male sex, being born abroad, and history of treatment failure were found to be risk factors for adverse treatment outcomes. Hence, patients with any of these characteristics should be carefully monitored and treated aggressively.