We evaluated the diagnosis of thrombus and the effect of antithrombic therapy by using 67Ga-DFO-DAS-Fibrinogen (67Ga-Fbg.) scintigraphy in vivo. The 11 patients with chronic renal failure had the operation of the internal A-V shunt. The two groups were divided the group I (the patients were injected 67Ga-Fbg. within 5 days after the operation of A-V shunt) from the group II (the patients were injected 67Ga-Fbg. from 7 months to 6 years after A-V shunt). We examined 72 h after the injection of 67Ga-Fbg. in all patients. In group I, the scintigraphy showed the deposition of 67Ga-Fbg. in all 5 patients, but 3 patients were given dipyridamole (75-300 mg). The scintigraphy examined 3 weeks after A-V shunt were negative in 2 patients in group I. In group II, the scintigraphy showed the deposition of 67Ga-Fbg. in the two of 6 patients. Within 5 day after A-V shunt, we observed there was the tendency of the thrombus formation. The scintigraphy of 67Ga-Fbg. was useful for the detection of thrombus in vivo.