Breast biopsy specimen radiography is required to ensure the accurate removal of clinically occult lesions discovered by mammography. Although used routinely for calcified lesions, it has not been widely accepted for those abnormalities that do not contain calcium. To determine the efficacy of film-screen specimen radiography for confirming the presence of clinically occult, noncalcified lesions, we undertook a prospective study of 104 specimen radiographs obtained after mammographically guided hookwire localization and planned excision of these lesions. Ninety-seven (93%) of the excised abnormalities were visualized on specimen mammograms. Malignancy was found in 22 (21%) of them. Thirty-five percent of the specimen radiographs showed better anatomic detail of the lesion, 48% showed the same detail, and 16% showed less detail than the original mammograms. Specimen radiographs failed to show the lesion in only seven cases. Five of the seven were true-negative specimen radiographs, making the efficacy rate 98%. Film-screen specimen radiography of clinically occult, noncalcified lesions is a highly effective procedure for correctly identifying the presence of a mammographic abnormality.