We carried out a retrospective study of the methods used to achieve an early diagnosis of 67 patients with pulmonary tuberculosis treated at our institute between 1984 and 1989. Sputum bacteriology was positive in 56 of the 67 patients, 22 were positive on microscopical examination of smears and on culture and 34 on culture alone. The 11 patients with negative sputum bacteriology were all diagnosed by fibreoptic bronchoscopy. In addition, 21 of the 34 smear-negative/culture-positive patients were examined by fibreoptic bronchoscopy and the initial diagnosis was made in 7 of these. Thus the initial diagnosis was made by sputum bacteriology in 49 cases and by fibreoptic bronchoscopy in 18 cases. The median number of days between obtaining a specimen and starting therapy was 7 days for sputum microscopy, 41 days for sputum culture, 7 days for microscopic examination of bronchoscopy specimens, 51 days for culture of the same and 19 days for biopsy. Fibreoptic bronchoscopy is therefore useful for the diagnosis of cases of tuberculosis in which tubercle bacilli are not detected in sputum and, in some instances, for an earlier diagnosis of smear-negative/culture-positive patients.