These experiments were carried out to investigate the effects of electrical stimulation on changes of physicochemical properties in Hanwoo steer and bull beef. Electrical stimulation was performed within 1 hr postmortem (SSOV, 90 sec.). Electrically stimulated sides(ES) showed more rapid pH decline than non-electrically stimulated sides(NES). L, a, b values of meat color in steers were higher than those of meat color in bulls, but there were no consistent effects of electrical stimulation on meat color, cooking loss and water holding capacity. Myofibrillar fragmentation index of sides treated with ES was higher than that of NES during storage significantly. Md ES sides consistently showed lower hardness when compared with control sides. Examination of the electron micrograph revealed the enlargement of sarcolemma and mitochondria. These results suggest that electrical stimulation may also improve tenderness of meat.