Use of the observation unit in the management of 150 consecutive patients sustaining blunt or penetrating thoracic trauma, and initially presenting with stable vital signs, normal physical examination findings, and normal chest x-ray studies, was reviewed. All patients requiring admission declared themselves within six hours, with the exception of one asymptomatic patient whose repeat x-ray study was slightly delayed. Of the 150 patients, 129 (86%) were spared hospital admission, and no increased morbidity or mortality could be associated with our policy of selective hospital admission.