Daily injections of DTPA, begun 3 days after administration of Pu239 to mice, were continued for various intervals of from 1–12 days. Significant increase in survival followed 8 or 12 days of DTPA. Treatment given for 12 days removed 43.2 per cent of the skeletal plutonium and reduced the fraction of mice with bone tumors by 42.5 per cent at the time the last control animal had died. Two days of therapy had less effect on removal and tumor incidence. Bone tumor rate increased with time after plutonium injection. It was lowered significantly by treatment given for 12 days.