[en] A lysosomotropic agent, the non-ionic detergent Triton WR 1339 (a poly-oxyethylene ether of formaldehyde polymers of octylphenol) is known to be stored in rat liver lysosomes. The results of a study made to determine whether Triton WR 1339 exerts an influence on the metabolic fate of monomeric ²³⁹Pu and ²⁴¹Am in the rat as well as on the removal of these nuclides by DTPA, since Triton WR 1339 and transuranic elements share the same deposition site, are reported. The influence of Triton WR 1339 on the ²⁴¹Am content (per cent of ²⁴¹Am dose) of rat organs (skeleton, liver, kidneys) at different times after Triton WR 1339 injection, the influence of the time of Triton WR 1339 injection on the ²⁴¹Am content (per cent of ²⁴¹Am dose) of the same rat organs, and the influence of Triton WR 1339 Zn-DTPA and the combination of them on the retention of monomeric ²³⁹Pu in the same rat organs (per cent of ²³⁹Pu dose), are shown in tabular form. The mechanism whereby Triton WR 1339 appears to shorten the biological half-life of ²³⁹Pu and ²⁴¹Am in rat liver is discussed. (U.K.)