A computer program Automated Nodule Detection System Version-1 (ANDS-V1) that locates candidate nodules (CNs) in a chest radiograph has been developed. The CN locations are displayed to a radiologist for further inspection. This program was tested on 37 chest radiographs that contain at least one nodule. At least one nodule in 92% (34/37) of the radiographs was detected by the circle detection program (untrained ANDS). Among the CNs detected in a chest radiograph are numerous false positives. The radiologist must inspect 45 sites on the film to be certain that all detected nodules had been inspected. The number of false positive sites presented for inspection is reduced by the Nodule Expert program. Only 10 CNs must be inspected for the radiologist to be confident of having inspected all nodules detected by the program. The true positive rate is 86% (32/37) when the Nodule Expert program is used. Features for discriminating among various classes of CNs are described.