Abstract: ~(125)I-labeled gelatin sponge was made by special technique. Healthy adult rabbits were anaesthetized by amytal. Then the thigh-bone was exposed and drilled a hole. The bone marrow and bone substance were taken out and the bone-cave was planted with ~(125)I-gelatin sponge. At 14 or 30 days after planing, the radioactivities of the liver, lung, kidney, genitals as well as the blood (obtained from car-vein every two days after planting)were measured. The results, showed that the radioactivity remained high in all of these tissues and bolld from the sixth day to the eighteenth day after planting. The biological half-life in abdominal cavity and bone were 8. 5 days and 9.2 days respectively. At 14 days after planting, liver spleen and kidney exhibited high level of radioactivity, while low radioactivity was found in other organs.