Verra-t-on se généraliser les bandes enherbées? On connaît l'intérêt de ces dispositifs dans les zones pentues pour diminuer l'érosion, le transfert des particules du sol et des fertilisants (nitrates notamment) vers les eaux. Reste à évaluer ? c'est le but du travail présenté dans cet article ? les possibilités de rétention des produits phytosanitaires par de tels dispositifs. An experiment is designed to evaluate the efficacy of grassed buffer strips in restricting the transfer of plant protection products to surface water. The paper describes the experimental setup used and the development of suitable experimental techniques (analytical methods particularly). Preliminary results show that soil particle and herbicide residue (isoproturon) transfers in presence of grassed buffer strips are greatly reduced. It seems that grassed buffer strips are in fact effective in limiting surface water contamination for this type of herbicide, at least. The study will continue for a few years (effect of climatic conditions) with various types of plant protection products with different mobility characteristics.