We have performed a retrospective evaluation to assess the effects of temporal subtraction in chest screening. Nineteen abnormal and 30 normal examples of chest CR screening images were selected, and a data set comprising current, previous, and temporal subtraction (T-sub) images were generated. Abnormal examples were chosen from cases with abnormal findings that were confirmed by subsequent CT scanning to need close examination. In the evaluation experiments, only current and previous chest images were displayed at first. After a radiograph observer judged the existence of any abnormal findings by the 5-step rating method, the same observer judged the case again using the T-sub image. Physicians of three different categories, namely diagnostic radiologists with clinical experience of two years or more, less experienced radiologists, and non-radiologists participated in the experiments. As a result of ROC analysis, it was confirmed that the use of temporal subtraction improves the Az value by about 10% overall. The Az value increase was more significant in the group of less experienced doctors. The ROC curves using T-sub image of these physicians approached those of the well-experienced radiologists. These results strongly indicate the clinical efficacy of the assessed system in chest screening.