A method is described of holding rats so that one individual alone may take their electrocardiograms. This method is also applicable to other small animals. The rats were studied for a period of 1 yr. Heart rate at the age of 4 wks. averaged 540/min. The rate fell steadily to an avg. of 405 at 1 yr. of age. The P-R interval was 0.04 sec. at 4 weeks and lengthened to 0.045 sec. at 1 yr. The QRS was 0.01 sec. at 4 wks. and lengthened to 0.015 sec. at 1 yr. In 5 of the 15 vit. E deficient rats the QRS lengthened to 0.018 sec. The T wave varied in length from 0.02-0.05 sec. in lead I and from 0.06 to 0.09 in leads II and III. The P wave always occurred on the descending limb of the previous T wave except in the occasional case of a heart rate below 400 per min. The R wave varied from 5.0 to 7.5 mv. in lead II and from 2.5-5.5 mv. in lead I. Lead III was intermediate. With the possible exception of a slight widening of the QRS complex in 5 of 15 test rats, there was no difference between the electrocardiograms of the vit. E deficient rats and the normal controls.