The T wave in leads II, V4, and V6 in the electrocardiograms of 1,401 consecutively entering 18-year-old male conscripts at a military processing center in 1975 were classified, and the relationship between the frequency of the T-wave changes relative to the psychosocial and medical data of the subjects was examined. One percent of the conscripts had a negative T in one or more of these leads, and twelve percent showed some deviation from the "normal T," usually a T wave of less than ten percent of the R-wave amplitude. A common finding was the presence of a "notch" in the T wave of lad V4 (a negative deflection in the middle of a positive T wave). Those with T-wave changes showed the same incidence of signs and history of heart disease as those with a normal T. However, those with an abnormal T showed higher heart rate and systolic blood pressure at rest. Further, they had more nervous symptoms and a higher consumption of alcohol and tranquilizers. These findings were as common in the larger group of flat T waves as in the smaller group with T-wave changes of the type normally attributed to organic heart disease (i.e., having notched, or more or less inverted T waves without ST depression). The maximal work capacity and vital capacity were slightly lower in subjects with abnormal T waves. However, this was fully explained by lesser height. It is suggested that in the majority of these cases, T-wave changes in young adults are due to increased sympathetic tone rather than to organic heart disease.