Specimen radiography with or without needle localization should become standard procedure when breast biopsy is performed solely on the basis of mammographic findings. Without these techniques, surgery may prove useless. Over a five-year period from 1974 through 1978, a series of 423 specimen radiographs were done at Memorial Sloan-Kettering Cancer Center for questionable mammographic calcifications or, in a few instances, nonpalpable masses. One hundred and twenty-six proved to be carcinoma, but they represent only 4% of the total number of cancers treated during this period of time. Most breast cancers are still being detected by palpation or palpation combined with mammography. The cancers needing specimen radiography or needle localization are the truly minimal lesions with the best prognosis. With present day techniques, radiation dosage from mammography is extremely low. Its continued use should be encouraged if mammography is to have any impact on breast cancer survival rates. High quality mammograms, interpretation by experienced radiologists, and close coordination of the efforts of the radiologists, surgeon, and pathologist can make possible the detection of increasing numbers of these minimal cancers.