Abstract 1. 1. The effect of meals on the electrocardiographic pattern was studied in 120 experiments on 12 normal young men. 2. 2. The electrocardiograms were taken before, thirty minutes after, and, in some cases, sixty minutes after standard mixed meals and high-fat content meals of 942 to 1,548 calories. 3. 3. The three standard limb leads were taken in all 120 experiments, and in 24 experiments chest leads CF 1, CF 2, and CF 4 were also taken. The results were analyzed by precise statistical methods. 4. 4. In the limb leads the significant changes observed were an increase of heart rate, increase of K QT (i.e., QT √R− R ), a decrease of the T wave, a decrease of the duration of mechanical systole, a decrease of the Q-T interval, an increase of the QRS amplitude, and a left axis shift of the T axis. 5. 5. Frequent but not consistent changes were observed in the P wave, range of heart rate, and K, calculated from the duration of mechanical systole. 6. 6. The P-R and QRS intervals, the Q-wave, and the S-T segment showed little change. 7. 7. The T wave in CF 1 became more positive; in CF 2 especially in CF 4, the T wave was decreased. 8. 8. The changes produced by the standard mixed meals and the high-fat meals were similar. 9. 9. The changes observed at thirty minutes after a meal were present with only minor variations at sixty minutes after a meal. 10. 10. Some practical applications to electrocardiographic procedure are discussed.