The paper chromatographic behaviour of uranium, lanthanum, samarium, europium, gadolinium and yttrium with tri-n-octylamine (TNOA)/ammonium nitrate system and the ascending technique was investigated. The Whatman No. 1 paper strip (1.5×21 cm) was treated with 0.3 ml of 0.2 M TNOA benzene solution, which had been saturated with twice its volume of 2 M nitric acid before use. As eluent, aqueous ammonium nitrate solution of different concentrations, acidified with nitric acid, was used. It took about two hours to develop the chromatogram. The relation between the R_F values of the elemenu mentioned and the concentration of ammonium nitrate (2-10 M, acidified with nitric acid to attain pH 2.4) was shown in Table 1 in the Chinese text. It was found that uranium(Ⅵ), lanthanum and samarium together with europium, gadolinium, and yttrium can be separated into three spots over a wide range of ammonium nitrate concentrations.