We endeavored to clarify the role of the shoulder girdle during the backstroke. Twelve muscles of the shoulder girdle in competitive swimmers with normal shoulders were studied with fine-wire electromyography (EMG). The results demonstrated a similar pattern of activation at hand entry and hand exit in the three heads of the deltoid, supraspinatus, and scapular rotators as they positioned the shoulder girdle for hand entry and exit. The latissimus dorsi, subscapularis, and teres minor were the primary muscles during the propulsive phase. The pectoralis major and infraspinatus revealed minimal activation throughout the stroke.