THE daily activities of all individuals encompass, from time to time, situations which are associated with heightened degrees of emotional arousal. We usually refer to these situations as “stressful”, and we have recognized that such feelings as anxiety, fear, anger, or rage may occur during these experiences. Over the past decades investigations of the physiologic responses that accompany intense feeling states have been made either in the laboratory during induced emotional arousal or following some actual stressful experience in daily life. The development of miniaturized telemetering equipment has made it possible for certain physiologic responses to be recorded before, during, and after, an, actual stressful situation, and this report is concerned with observations of heart rate utilizing such a technique. The subjects of this study were physicians working in this medical center. The daily activities of physicians include several experiences which may be considered to be “stressful”. For the purposes of initial observation three situations were chosen: (1) The mid-day staff conference during which patient history presentations and discussion were conducted, (2) medical student presentations of patient examinations during attending staff ward rounds, and (3) diagnostic cardiac catheterization in the cardiac catheter laboratory. These situations were accompanied by varying degrees of anxiety in all physicians, and were considered by all participants to fit the general category of “stressful”. The individual variations in the physiologic response are of particular interest, however, and form the content of this report. METHOD The method used in this laboratory for radiotelemetry of the pulse rate has been previously reported [l]. The several modifications used in this study, included the following: the electrocardiogram, after being transmitted from the subject to the central receiving station, was also recorded on magnetic tape for future playback on standard electrocardiographic paper. This allowed subsequent direct measurement of the R-R interval providing a check on the value of heart rate recorded by the cardiotachometer. For the mid-day staff conferences, the physician who was to present the patient history was brought to the laboratory prior to the conference and the electrocardiograph transmitter applied. Anterior and lateral chest leads were used and the transmitter was worn either in a shirt pocket or in a speciallyfitted holster. The heart rate was recorded during the entire hour of the conference: before, during and after the actual patient presentation. The mean rates were calculated for each period in addition to the peak change during the presentation. The medical students observed during ward rounds were recorded throughout the full morning rounds, which also included periods of time when the student was not presenting a patient history, but merely observing other members of the group. The physician performing the cardiac catheterization wasrecorded from approximately a half hour before, to the final completion of the study. Particular stressful moments during the procedure were