This study was designed to assess the diagnostic efficacy of the routine lateral chest film in symptomatic newborn infants. The initial anteroposterior chest film was supplemented by alateral view in 53 consecutive patients on admission to the newborn intensive care unit. Subsequently three radiologists and two neonatologists performed independent analysis of the anterposterior films with and without the lateral view. A total of 530 observations were tabulated. Assessment of degree of lung inflation and discovery of abnormalities of the heart, mediastinum, and trachea were unaffected by the use of the lateral radiograph. A correct primary diagnosis was made in 74% of all cases by the anteroposterior chest film alone and in 71% by the anteroposterior/lateral series. Degree of confidence in the primary diagnosis did not change when the lateral chest radiograph was added. There was no appreciable difference in detection of complicatins of the primary disease in either series. We conclude that the risks (e.g., radiation and environmental disturbance) of the routine admission lateral chest radiograph are substantially greater than any benefits to be gained.