Exercise electrocardiograms (Ex ECG) were performed on both trained and untrained adolescent males to determine whether a difference exists between the normal adolescent and normal adult male. Exercise was performed on a mechanically braked bicycle ergometer using an intermittent work load protocol, and the Ex ECG's were analyzed according to J-point displacement and ST segment slope. No J-point depression was seen and the ST segment slope was positive during exercise in both trained and untrained subjects. There was no difference in the J-point displacement or the ST segment slope between the trained and untrained subjects. This study suggests that any J-point depression during exercise may be abnormal in the adolescent male. Training does not have an effect on the J-point or ST segment at maximum exercise.