The transactions of the fifth and final conference on shock and circulatory homeostasis, sponsored by the Josiah Macy Jr., Foundation, brings to the reader the deliberations of a distinguished group of investigators from a variety of professional disciplines, all of them having strong interest in this field, reflected in their substantial contributions to it. Each of the topics, which include the role of hepatic blood flow, bacterial factor, protection afforded by Aureomycin, blocking agents, humoral factors, hypothermia and chlorpromazine, and the lymphatic system as related to experimental shock, is introduced by the presentation of the methods and results of the researches by one of the participants. Experiments conducted in the germ-free rats and the hepatic ferrintin systems are also discussed. The presentations served as a departure point for the recorded informal discussion by the participants. Each of the nine sections includes a current and useful bibliography, tables, and diagrams of