The effects of the oral administration of CBMIDA [catechol-3, 6-bis (methyleiminodiacetic acid)], given in drinking water, on the removal of plutonium in rats were compared to those of Zn-DTPA. Male Wistar rats received a daily dose of 120μmol/kg or 1, 200μmol/kg of CBMIDA or Zn-DTPA, given in drinking water, for 4 weeks after plutonium injection. The content of plutonium in bone, liver, kidney, spleen, and testis was measured by a liquid scintillation spectrometry after treatment of the organs by a wet ash method. The plutonium content of each organ in the 120μmol/kg groups of CBMIDA and Zn-DTPA was not significantly reduced. The content of plutonium in the 1, 200μmol/kg groups of both CBMIDA and Zn-DTPA was, however, significantly reduced, to 65.7% (p<0.001) and 76.8% (p<0.05), respectively of the control in bone, and to 66.6% (p<0.05) and 44.0% (p<0.01), respectively, in liver. There were no significant decreases in kidney, spleen, and testis in the 1, 200μmol/kg dose CBMIDA group, but there were significant decreases in these organs in the 1, 200μcmol/kg dose Zn-DTPA group. These results showed that, when given orally, CBMIDA was more effective in removing plutonium from bone than Zn-DTPA, a finding similar to the results were achieved with the intravenous injection of both agents in our previous study.