The aim of this study was to evaluate the usefulness of novel color digital summation radiography (CDSR) for detecting solitary pulmonary nodules on chest radiographs by observers with different levels of experience. A total of 30 healthy controls and 30 patients with newly detected solitary pulmonary nodules were evaluated. Six radiologists and five residents evaluated three image sets: set A, current and prior radiographs only; set B, set A with temporal subtraction images; and set C, set A with CDSR. The observers were asked to rate each image set using a continuous rating scale. In addition, the reading time required for each set was recorded. The radiologists showed no significant differences in the mean A(z) value between set A, set B, and set C. However, the residents showed significant differences between set A and set B and between set A and set C. In addition, for set B and set C, the mean reading time per case of all readers was significantly shorter than that for set A. The detection capability of observers with little experience is comparable to that of experienced observers when reading radiographs with temporal subtraction images or with CDSR. The usefulness of CDSR is comparable to that of temporal subtraction.