All detected abnormal findings were recorded for 1085 consecutive chest x-ray examinations. Each finding was classified by descriptive criteria and graded for subtlety. Accuracy of interpretation was evaluated in a randomized sample of 100 cases using follow-up or multiple readers. Seventy percent of standard examinations and 93% of bedside examinations revealed abnormal findings. Pulmonary infiltrates were the most commonly detected abnormality, being present in 55% of abnormal cases. Noncalcified pulmonary nodules and pneumothoraces were each present in approximately 5% of abnormal cases. The most commonly encountered subtle findings were due to intravenous catheters, pulmonary infiltrates, pneumothoraces, rib lesions, and pulmonary nodules in descending order of frequency. It is concluded that it is reasonable to use selected examples of these findings in observer tests when evaluating new imaging modalities such as digital radiography.