Radiographic manifestations of aspiration of gastric contents were reviewed in 60 patients. The findings were extremely variable, and there was no typical or characteristic appearance. Confluent and acinar infiltrates, as well as infiltrates composed of small irregular shadows, occurred singly or in a variety of combinations; the third pattern predominated in the majority of cases. Distribution was most commonly bilateral and multicentric and usually favored perihilar or basal regions, but localized or atypical densities were also observed. Patients with the most extensive radiographic abnormalities on initial studies tended to have the worst prognosis; however, mild early pulmonary infiltrates occasionally progressed to life-threatening abnormalities, and extensive initial involvement was frequently followed by a benign clinical and radiographic course. Radiographic changes often worsened for several days in uncomplicated cases, but improvement was generally manifested within the first week after aspiration. Worsening of infiltrates after initial improvement was associated with the development of bacterial pneumonia, the adult respiratory distress syndrome, and pulmonary embolism. In the appropriate clinical setting, aspiration of gastric contents should be an important diagnostic consideration in the presence of a wide variety of radiographic changes.