An understanding of the speciation of uranium(VI) (uranyl ion, UO22+) in blood medium is very important for investigations of internal contamination. Studies have been performed on the speciation of uranium(VI) in the presence of phosphate and blood serum using time-resolved laser-induced fluorescence (TRLIF) and capillary electrophoresis (CE). By TRLIF it is possible to identify spectrally and temporally, by comparison with distribution curves calculated using data from the OECD database, UO2H2PO4+, UO2HPO4 and UO2PO4- species. Results concerning the study of the uranium(VI)-blood plasma system are presented. CE has demonstrated that it is possible to separate human gamma-, beta-, alpha2-, and alpha1-globulins and albumin in the presence of uranium(VI).