In case of the acute intake of radionuclide, an early medical treatment may be necessary, but the little is established the procedures to decontaminate the victims of internal contamination in Korea. The purpose of the present investigation is to study chemical agents to remove radiocobalt from the victims and to provide a more reliable procedure for the treatment. The removals of radiocobalt from the NIH-CGP)mice injected intraperitoneally with $1{mu}Cio;f^{58}Co;as;CoCl_2$ were investigated with doses of either $CaNa_3$ DTPA 8.4mg/0.2ml saline, $CoNa_3$ DTPA 8.4mg/0.2ml saline, or saline 5ml. The radioactivity was determined by MCA and Ge-detector on 4, 8, 12, 48 hours and 7 days for the whole body, organ distribution and urine excretion. Six mice per each group were sacrificed for the measurement of cobalt retention in the parenchymal tissue. The cobalt trisodium chelate had a pronounced effect on reducing the whole body retention and increasing the excretion rate. Regarding to the systemic protective effects, $CoNa_3$ DTPA, $CaNa_3$ DTPA and saline were effected significantly in order. In conclusion, the extrapolations from these results to human were suggested that the rapid administration of cobalt trisodium chelate and an amount of saline to the contaminated person after internal contamination of radiocobalt were markedly increasing the decontamination effects.