We performed a study to determine whether clinical history gives a positive or negative influence on X-ray film interpretation. One hundred and nine patient's radiograms, consisting of 55 normal and 54 abnormal cases (136 abnormalities), were interpreted twice by three pairs of residents in radiology and a pair of qualified radiologists, without clinical history first and with clinical history next. The interpreters recorded diagnosis and confidence level of normal or abnormal findings on a six-point scale. Analysis of receiver operating characteristic (ROC) curves showed that knowledge of clinical history improved diagnostic accuracy. Residents, especially beginners, should be advised to obtain clinical history whenever they read radiograms.