The value of the lateral chest radiograph, often considered a useful adjunct in the detection of hilar adenopathy, was evaluated in a prospective study of 449 children assessed for tuberculosis. Of these children 298 presented to the hospital with signs and symptoms suggestive of tuberculosis, while 151 were investigated in a regional clinic solely because they were in close contact with an adult household member on treatment for tuberculosis. Tuberculosis was confirmed by culture in 176 of the 449 children (39%). In 40 of these (23%) hilar adenopathy was visible on frontal and lateral view, in 19 of the 176 confirmed cases (11%) only on a frontal view and in 22 (13%) on a lateral view only. Probable tuberculosis was diagnosed in a further 140 of the 449 children (31%), and hilar adenopathy was visible on frontal and lateral views in 39 of these children (28%), on the frontal view only in 8 (6%) and on the lateral view only in 27 (19%). In the symptomatic children investigated in the hospital, and the asymptomatic children investigated in the clinic, hilar adenopathy was detected on the lateral chest radiograph only in 36 (12%) and 14 (9%) cases respectively. Lateral chest radiographs will considerably improve the accuracy of the diagnosis of childhood tuberculosis.