Uranium can be leached with a mixture of nitric and perchloric acids from 1 g of marine or lacustrine sediment in an autoclave at 275 degrees and 2 atm in 4 hr. The leachate resulted from this steam digestion may then be analyzed for uranium by isotope dilution alpha spectrometry with a precision of about +/- 7%. In comparison to the conventional leaching scheme by wet digestion in an open beaker, this method is less time consuming, less labor intensive, requires the use of smaller amounts of acids while it yields data with comparable accuracy and precision. In the analysis of a set of samples collected from a variety of depositional environments, this method yielded results that were indistinguishable from those obtained by the conventional method.