The use of ammunition containing depleted uranium (DU) in several military actions is of growing health concern to the population related to the risk arising from contamination of the environment with DU penetrators and dust. Environmental monitoring of uranium and its isotopic ratios therefore become important parameters since they allow for source identification. Neutron activation analysis according to the k0-standardisation not only allows for quantification of trace elements including uranium, but it can also provide information about the 235U/238U isotope ratio. The application of this method as a screening technique to moss samples, as a bio-indicator for this atmospheric pollution, was evaluated for samples spiked with different 235U/238U isotope ratios. Detection limits of about 0.6 ng/g and 6 ng/g were obtained for 235U and 238U, respectively. The concentration of natural uranium found in moss samples is however the limiting factor, reducing the quantification limit for DU to 400 ng/g.