A method for assessing the mass concentration of uranium in a sample of uranium-bearing material by gamma spectrometry, includes a) acquiring (200) an energy spectrum of gamma radiation from the sample using a scintillator detector, the energy spectrum (100) comprising at least a first energy band (110) between 87 keV and 110 keV, and a second energy band (120) between 560 keV and 660 keV, the second energy band comprising at least one energy line (130) at 609 keV from 214Bi, b) calculating (210) an initial mass concentration of uranium (CmU0) using the energy spectrum, c) measuring (220) a parameter representative of the height of the sample and a parameter representative of the density of the sample, d) calculating (230) a corrective coefficient (K), and e) calculating (240) a corrected mass concentration of uranium (CmU) using the initial mass concentration of uranium (CmU0) and the corrective coefficient (K).