Under the auspices of the International Union of Physiological Sciences, the Federation of Hungarian Medical Societies and the Hungarian Physiological Society a Symposium was organized on the "Neurohumoral and Metabolic Responses to Injury" in Budapest August 3-7, 1971 as a satellite symposium to the XXV Congress of Physiology. The aim of this multidisciplinary Symposium was to concentrate on the neurohumoral and hormonal aspects of the biological response to trauma including resistance and adaptation to injury. It is becoming increasingly apparent that the changes which occur after injury reflect the disturbance of regulatory processes and control mechanisms concerned with the preservation of homeostatic equilibrium. One of the main aims of the Symposium was to consider the effect of injury on control mechanisms. It was thought advisable to include speakers more closely associated with the study of control mechanisms under normal conditions in order to ensure cross-fertilisation of ideas between the physiological and pathophysiological fields. The Symposium provided an excellent setting for discussions both inside and outside the meeting. These could not be included in the report of the proceedings but it is hoped that they will lead to renewed efforts in research into these often neglected, but clinically important, problems.