Abstract: A method for determination of uranium in sandstone uranium geological samples by isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) was evaluated. Samples were digested and spiked with highly enriched uranium (HEU) in a closed vessel using mixed acids, and ²³⁵U/²³⁸U ratio was measured by high resolution ICP-MS. The method is capable of determining uranium contents of 1-10 000 μg/g with relative expanded uncertainty of 4.0% at uranium contents of 4 μg/g, and is qualified for the arbitral analysis of uranium in sandstone uranium geological samples.