[en] Over a number of years, the Chemistry Division of AWRE, Aldermaston, studied the nature of plutonium in various biological systems. The object of the work was to identify those natural products of the body which play a part in the transport and deposition of accidental intakes of plutonium. These results should be of value in formulating more effective therapeutic measures for plutonium removal from the body. The paper reviews the work at AWRE on the interaction of plutonium with serum and rat liver. Experiments on the uptake of plutonium into cell cultures are described. The aim of these experiments was to see whether a model system could be set up for testing the efficacy by which chelating agents could remove plutonium from within cells. A simple hypothesis is presented for the mode of transport of plutonium within animals. (author)