Experiment of electrical stimulation using direct current on the tibia of normal adult rabbits was performed for the duration of 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks, and 8 weeks. The cathodic electrode, Teflon coated Kirschner wire used in clinical work was introduced into the medullary cavity of the proximal tibia from the tibial tuberosity and the anodic electrode was introduced transversely in the metaphysis of distal tibia on the same side. Twenty micro-ampere of direct current was passed continuously through the fixed wires between the proximal and distal tibia on left side. At the end of first week, second week, third week, fourth, sixth, and eighth week, anodic and cathodic electrode were removed and animals were sacrificed and tibia was obtained for specimen, and then X-rays were taken, and the specimens were decalcified and stained with hematoxylin and eosin. The new bone formation in the medullary canal were measured by the degree of filling in the marrow canal as percentage by the point counting method. The results were as follows. First, Endosteal new bone formation is a main feature, and also periosteal reaction was noted in 27 % of cases. Second, In the first week group, new bone formation is minimal and difference between groups, that is, second, third, fourth, sixth and eight week group, the degree of new bone formation is statistically insignificant. Therefore possibility of short term electrical stimulation of duration of two week or four week is contemplated clinically.