The atomic bombs dropped on Hiroshima and Nagasaki in August, 1945, unleashed a force as mysterious as it was deadly. In 1946, the Atomic Bomb Casualty Commission (ABCC), under the auspices of the Atomic Energy Commission (AEC), was formed as a permanent American agency in Japan with the official mission of studying the medical effects of radiation on the survivors. The next ten years saw the ABCC's most intensive research on the genetic effects of radiation, and up until 1974 the ABCC scientists published papers on the effects of radiation on ageing, life span, fertility and disease. This text provides a comprehensive history of the ABCC's research on how radiation affected the survivors of the atomic bomb. Arguing that Cold War politics and cultural values fundamentally shaped the work of the ABCC, it describes how the project raised disturbing questions about the ethical implications of using human subjects in scientific research. How did the politics of the emerging Cold War affect the scientists' biomedical research and findings? How did the ABCC document and publicly present the effects of radiation? Why did the ABCC refuse to provide medical treatment to the survivors?Through a detailed examination of ABCC policies, archival materials, the minutes of committee meetings, newspaper accounts and interviews with ABCC scientists, Lindee explores how political and cultural interests were reflected in the day-to-day operations of the research programme.