A coprecipitation method using Fe(OH) 3 as carrier, previously studied for preparation of alpha spectrometric sources of actinides, was applied to uranium samples. The results point to a special behaviour of U(VI). Although chemical recoveries were lower than those obtained for actinides such as plutonium, americium and thorium, they were strongly dependent on the concentration of U(VI) in the sample. Quantitative yields were obtained when the concentration of U(VI) exceeded 16μg/ml. The influence of concentration on the FWHM obtained are also discussed.