The study aimed to compare ten assessment procedures for nutrient emissions to inland waters arising from diffuse agricultural sources. Eight European Union Member States have independently developed these procedures. They essentially relate emissions to the characteristics of the sources and of the medium. The procedures have been systematically compared according to a matrix of criteria dealing with the components integrated within the model, the presentation of the results and the scale of application. It can be concluded that the principles of these procedures are homogeneous. Thus, the implementation of a future harmonised methodology for all Member States of the European Union seems to be feasible.