We compared the sensitivity of gastric lavage (GL) with bronchoalveolar lavage (BAL) for isolating Mycobacterium tuberculosis (Mtb) from 20 children with a presumptive diagnosis of primary pulmonary tuberculosis. GL was performed on three consecutive mornings after an overnight fast. BAL was performed on the same day as the last GL. Specimens were submitted for smears and culture for Mtb. None of the acid-fast stained smears was positive. Cultures of BAL fluid on 2 patients (2 of 20 or 10%) were positive for Mtb. Cultures of the gastric aspirates from the same 2 patients were also positive for Mtb. Eight additional patients had positive GL cultures with negative BAL cultures, resulting in a total of 10 of 20 (50%) patients with positive GL cultures for Mtb. The results of our study indicate that GL done on three consecutive days is better than BAL for the bacteriologic diagnosis of childhood pulmonary tuberculosis.