To assess the radiologic patterns of presentation of active pulmonary tuberculosis, the authors studied all patients with active, culture-proven pulmonary tuberculosis who presented in British Columbia between May 1989 and May 1991. The chest radiographs were assessed by two observers. Epidemiologic data were collected to allow examination of differences among ethnic groups. The 188 patients ranged in age from 1 to 96 (median 54) years; only 2 were less than 20 years of age. Thirty of the 188 patients (16%) presented with clinical and radiologic findings consistent with primary tuberculosis; the other 158 (84%) had postprimary disease. Of the second group, typical upper lobe infiltrates were seen in 126 (80%). Less common manifestations included lymphadenopathy (in 14 cases), isolated nodular tuberculoma (in 10), isolated involvement of the lower lung zones (in 10), cavities with air-fluid levels (in 6) and isolated pleural effusion (in 2). The authors conclude that the characteristic upper lobe infiltrates of postprimary disease remain the most common form of presentation of active tuberculosis in adults. However, atypical presentation, due to either an unusual pattern of postprimary tuberculosis or to primary tuberculosis, may be seen in up to 30% of patients.