SUMMARYExperience with a maximal treadmill stress testing procedure which is relatively safe, simple, and reproducible is reported. It Circulation, Volume XXXIX, April 1969 Peak predicted pulse rates were chosen for detailed analysis. Information as to their previous health was only known for 284 executives previously examined and thought to be normal by history and resting ECG. Many of the remainder were sent for evaluation of known or suspected angina, and many were sent for screening prior to embarking on a physical fitness program. Careful questioning as to symptoms, medication, and previous cardiac disease was done to rule out unstable coronary insufficiency and congestive failure. In the group were 205 females and 795 males with ages varying between 7 and 83 years.No special attempt was made to standardize the time of day or the relationship of the last meal.The patients are prepared by applying gel (Lectrocardiographic Gel) to the Telectrode electrode and affixing these self-adherent electrodes to the upper part of the manubrium sterni and the standard left chest V5 position (CM-5).5 The cable attachments are then snapped to the electrodes and the cable is connected to a directwriting Sanborn electrocardiograph. The electrocardiographic complexes are monitored continually with an oscilloscope. An aneroid sphygmomanometer is placed on the right arm for measurements of blood pressure. A cardiotachometer gives a constant read-out of the heart rate. Oxygen, emergency drugs, and a DC defibrillator are available in the room.Resting electrocardiograms are taken while the patient is sitting and also while standing, before and after hyperventilation, and are used