Tuberculosis as a primary cause of respiratory failure requiring mechanical ventilation (TBMV) is an uncommon occurrence. Over a 10 yr period in the province of Manitoba, Canada (population 1,091,942 in 1991), 13 patients with TBMV were identified. Non-drug-resistant M. tuberculosis was isolated from each case. The patients fell into two categories: miliary or disseminated tuberculosis (n = 7) and tuberculous pneumonia (n = 6); eight developed ARDS (adult respiratory distress syndrome) and another two probable ARDS. The hospital mortality for TBMV was compared with that for mechanically ventilated nontuberculous pneumonia and ARDS patients. Hospital mortality for patients with TBMV (69%, nine of 13) was significantly worse than hospital mortality for patients with nontuberculous pneumonia requiring mechanical ventilation (36%, 34 of 94; p < 0.025) and similar to the hospital mortality for patients with ARDS of any cause (56%, 15 of 27; p > 0.10). APACHE II scores for all groups of patients were similar. Compared with patients with tuberculous pneumonia, patients with miliary or disseminated tuberculosis were significantly more likely to develop TBMV (18.9 versus 0.8%, p < 0.0001). Despite the availability of effective antituberculous drugs, TBMV is often associated with ARDS and carries a similarly high mortality rate. Among patients with pulmonary tuberculosis, those with miliary or disseminated disease are especially prone to develop TBMV.