Mammography is one of the most oversold and understudied technologies in medical history. To continue to assert that mammography will save lives flies in the face of huge numbers of studies on the topic. Individual doctors treat individual women but do not and cannot study the patterns of disease in populations. That is the job of epidemiologists and other public health experts. Their work on the hard numbers confirms the sorry truth–mammography regularly used in women under age 50 produces more harm and does not reduce deaths.