Gamma-spectrometric methods suitable for the characterization of highly enriched uranium samples encountered in illicit trafficking of nuclear materials are presented. In particular, procedures for determining the U, U, U, U and U contents and the age of highly enriched uranium are described. Consequently, the total uranium content and isotopic composition can be calculated. For determining the U and U contents a low background chamber was used. In addition, age dating of uranium was also performed using low-background spectrometry.