The siderophone analogue 3,4,3-LIHOPO, referred to hereafter as LIHOPO, has been examined for its ability to remove 238Pu in a tributyl-n-phosphate (TBP) complex from rat after intramuscular (i.m.) or subcutaneous (s.c.) contamination. The chelating agent was administered at a dosage of 30 mumol.kg-1, 30 min after the contamination, either by intravenous (i.v.) or local injection. By day 7 after exposure, local (i.m.) administration of LIHOPO reduced the amounts of i.m.-injected 238Pu in the would site, skeleton and liver to 75, 20 and 25% respectively of those in untreated animals. At the i.m. Pu would site, local treatment was superior to i.v. treatment; both ligands were equally effective. At the s.c. Pu would site, local and systemic treatments were equally effective and LIHOPO was superior to DTPA. After translocation, LIHOPO was the most effective treatment for enhancing Pu excretion, whatever the route of contamination and treatment: the administration of LIHOPO and DTPA reduced whole-body Pu retention by a factor of 1.8 and 1.4 respectively. All these results are encouraging for the use of LIHOPO in the future but more studies are needed, concerning both the toxicity of the compound and its use in man.