A plan for Post Market Environmental Monitoring (PMEM) of genetically modified (GM) plants is mandatory in all applications for deliberate release submitted under EU Directive 2001/18/EC and EU Regulation 1829/2003.  PMEM is composed of case-specific monitoring and general surveillance of GM plants.  The European Food Safety Authority (EFSA) is responsible for assessing the scientific quality of PMEM plans submitted with each application.  In a scientific opinion, the EFSA GMO Panel presented specific guidance for applicants for developing PMEM plans.  In addition the EFSA GMO Panel explained the scientific rationale for this guidance and makes a number of recommendations for the management and conduct of PMEM by both applicants and risk managers.  Until the end of March 2007, the EFSA GMO Panel gave opinions on 11 PMEM plans submitted under EU Directive 2001/18/EC and another 11 plans submitted within applications under EU Regulation 1829/2003.  Currently 27 applications for GM plants are still in the evaluation process and the EFSA GMO Panel sent 26 questions to the applicants for clarification and additional information during the evaluation process.  Sixteen of these questions were related to General Surveillance (e.g. general structure, farm & operator questionnaires, integrations of identity preservation systems, use of existing surveillance systems, feral plant surveillance).  Nine questions requested clarification on the environmental risk assessment, which might effect whether case-specific monitoring is needed.  In one case (an application for cultivation of a GM crop), the GMO Panel recommended case-specific monitoring.  We explain in more detail how the environmental risk assessment of two Bt maize dossiers (maize Bt11 and 1507) were considered by the GMO Panel in the evaluation of the PMEM plan and the consequences for the environmental monitoring plan.  As stated in the EFSA opinion on post-market environmental monitoring, the general surveillance plans shall, when possible, make use of existing monitoring systems in addition to more focused monitoring systems.  However, the use of these national monitoring programmes is outside of the management and control of an individual applicant and thus it cannot be the task of an applicant alone to use, modify or improve existing surveillance systems.  The availability of biodiversity monitoring programmes in the EU Member States should be evaluated by applicants in close liaison with risk managers.