The extraction of the small quantities of uranile-ions out of water  solutions   has been studied.  It  is established that  chlorinated naphthenic acids are effective extragents of uranium from water solutions containing great quantities of salts of alkaline metals. pH_1/2  extraction considerably shifts into acid (in the presence of chlorides) or alkaline sphere (in the presence of sulphates) depending on ammonic composition of salts and their concentration that permits to increase choiceness of extracting uranium. Effectivity of extracting uranium is considerably improved in the presence of minimum quantities of aniline or that of other amines. High effectiveness of extraction of  uranium in the presence of aniline and under relative constancy of extraction in a wide interval of acidity of water phase served as foundation for working out the method of determining small quantities of uranium chlorinated by naphthenic acids.