In Europe holders of authorisations for genetically modified (GM) crops are required to monitor for the occurrence of any unanticipated adverse effects on human health and the environment resulting from the importation or cultivation of a GM crop. General surveillance was instituted to ensure that if any unanticipated adverse effects occur, measures can be taken to protect human health and the environment. Since 2010 most applicants have submitted the same monitoring plan. Although COGEM considers this monitoring plan to be adequate for the importation of GM maize, soy and cotton, it sees a number of opportunities for improvement, as recommended in previous topic and advisory reports. COGEM realises it makes little sense to include these suggestions for improving the GS plan in every advice. Therefore COGEM decided to set out these points in this advisory letter and refer to them where relevant in future advice on permit applications for marketing authorisation.