Patients with active tuberculosis (Tb) can be admitted to hospital due to other health problems, Tb not being the admission diagnosis. In this study, the authors analyzed 141 inpatients with Tb, notified to the São Paulo Hospital Central Control of Infectious Diseases, during the period of august, 1999 to April, 2001, trying to identify causes of admission, risk factors, and duration of hospitalization. Of the total number of patients, 63% were male and 37% female, mean age being 38 years-old. 28% were smokers, 23% were alcoholics, and 17% were drug addicts. 23% of them reported previous Tb. 42% were HIV positive. 54.6% of the patients presented pulmonary tuberculosis and 67.5% of them had positive sputum. 22% of the patients had side effects to Tb treatment during hospitalization, drug-induced hepatitis (65.7%) and gastric intolerance (25.7%) being the most frequent. 8.5% of the patients required intensive care, staying there for 11 days, and 54% of the patients stayed at an infirmary with respiratory isolation. 17.7% of the patients died in hospital and 52% due to Tb. The patients were hospitalized for 29 days and isolated for 18 days. Drug addicts and smokers patients had longer hospital stays. HIV positive patients who had positive sputum had the same hospitalization period as others.