Interferon-alpha (IFN-alpha) is a cytokine exerting pleiotropic activities, including antimicrobial effects, especially directed against intracellular infectious bacteria. It may be administered by aerosol to reach the lower respiratory tract without systemic side effects. The aim of the study reported here was the evaluation of aerosolized IFN-alpha treatment (3 MU/dose, given three times a week; total study dose: 72 MU/2 mo) in combination with conventional antimycobacterial therapy in patients with pulmonary tuberculosis. Two groups of 10 patients each were compared before and after 2 mo of conventional antituberculous chemotherapy with or without inhaled IFN-alpha. Several biologic (bronchoalveolar lavage fluid [BALF] cellularity, Mycobacterium tuberculosis [MT] number in sputum), biochemical (BALF concentrations of 10 cytokines, BALF IFN-alpha receptor levels), and clinical (fever, vital signs, high-resolution computed tomography [HRCT] images) measures were made in these patients at the time of their enrollment and at the end of the observation period of the study. Fever, MT number in sputum, and abnormalities in HRCT images showed significantly earlier resolution in the IFN-alpha-treated group, together with a more significant decrease in BALF interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor-alpha (TNF-alpha) concentrations and significantly greater pre- versus posttreatment variations in IL-2 and IFN-gamma. These data, taken together, suggest that IFN-alpha administration may favorably affect the evolution of pulmonary tuberculosis when combined with antimycobacterial therapy.