[en] Inter-laboratory tests are a means of assessing the analytical coherence of medical laboratories. In radiotoxicology, this kind of exercise makes it possible to keep up with laboratory know-how and with the evolution and relative performances of analytical techniques. The intercomparison exercises organised by PROCORAD (Association for the Promotion of Quality Controls in Radiotoxicological Bioassays) provide an opportunity to compare and contrast radiochemistry and metrology for the in vitro analysis of urine and faeces. For uranium compounds, the development of new techniques such as inductively coupled plasma-mass spectrometry, alpha spectrometry, and laser spectrofluorimetry makes it possible to compare the effectiveness of these protocols with respect to radiation protection monitoring, both in routine and special situations. Detection limits, flexibility, repeatability, reproducibility and isotopic quantification are the criteria considered in this study. The authors present the evolution of performances for analysis of uranium in urine over the years. However, the goal of the laboratories taking part in these annual exercises is not only to check the accuracy of their results, but also to have analytical discussions and the opportunity to exchange experiences that will enrich the group's general competence. (author)