The features of community-acquired acute lower respiratory tract infections in 390 children are described. Half (50%) presented with bronchiolitis, 37% with pneumonia and 13% with croup. Respiratory syncytial virus was the commonest agent identified (52% of bronchiolitis, 29% of pneumonia, 51% of croup). Positive bacterial blood cultures were obtained in 10% of the patients, all except one with pneumonia. Fever (> 39 degrees C), a toxic ill look, bronchial breathing, WCC > 20 x 10(9)/l, neutrophils > 5 x 10(9)/l, platelet count > 500 x 10(9)/l, ESR > 45 mm/hr, lobar consolidation and pleural effusion were more likely to be associated with bacterial than with viral pneumonia (relative risk > 1.81; p < 0.05). In areas with limited resources, a high fever, a toxic ill look, bronchial breathing and simple laboratory tests may help to identify patients with bacterial pneumonia.