The European Food Safety Authority (EFSA) asked the Panel on Plant Protection Products and their Residues to prepare a scientific opinion on the Food and Environment Research Agency guidance proposal “Guidance on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessments”. The Panel concluded that the experimental and modelling approaches described in the proposed guidance are reasonable compromises between the required effort and what is desirable from a theoretical point of view. However, the Panel has concerns about the interpretation of the experiments and how the results of the experiments should be used in the leaching assessment. The Panel investigated options for improvement, but could not complete its evaluation on these two topics because underlying data to test these options were not made available to the Panel. For this reason, the Panel prepared a statement instead of a scientific opinion. Therefore, the Panel cannot recommend the use of the guidance for the time being.