Of approximately 6000 admissions to the Henry Ford Hospital medical ICU between October 1969 and September 1984, 61 (1%) had active tuberculosis (TB). Forty-three (70%) of these 61 had acute respiratory failure (ARF). TB was considered to be the sole cause of ARF in 12 and contributory in 31. Eighteen patients with TB but without ARF were admitted for treatment of other critical illnesses. Alcoholism was present in 31 (51%) of the TB patients. Only one of 12 whose ARF was caused primarily by TB had a history of known TB at the time of admission. Important factors contributing to ARF in TB patients included Gram-negative pneumonia and/or sepsis, chronic obstructive pulmonary disease, prior TB with anti-TB medication noncompliance, and malignancy. Six patients were not suspected of having TB when admitted to the medical ICU; three patients who had not been treated for TB were found to have TB on autopsy. The inhospital mortality rate for all patients with TB requiring intensive care was 67%, but was 81% in those with ARF.