The effects of muscle fatigue on the electrical activity of muscle have been studied in five normal subjects with a total of twenty recordings by a quantitative electromyographic method of converting voltage into frequency pulses. The relation between the progressive increase of electrical activity from a sustained static contraction of the anterior deltoid muscle and the time of contraction was found to be linear. It was also found that, in most individuals, electrical activity increases as the anterior deltoid muscle becomes fatigued. The method of electromyography used showed a moderately high correlation coefficient for reliability.