This second edition of the 1949 classic volume on atomic medicine has been brought up to date by thorough revision of the text and expansion of the bibliography. The basic physics, biology, pathology, and clinical effects of ionizing radiations are well discussed. The chapters on the biologic and clinical applications of radioisotopes are excellent. A chapter on dosimetry has been added. While there is a certain amount of repetition, inevitable in a book written by 20 contributors, the general level of presentation of facts and concepts is on a high plane of accuracy, clarity, and interest. This new edition fully deserves a very wide distribution.