The European Food Safety Authority (EFSA) is requested to assess the scientific quality of Post Market Environmental Monitoring (PMEM) plans submitted with each application for deliberate release of genetically modified (GM) plants according to part C of EU Directive 2001/18/EC and according to EU Regulation 1829/2003. PMEM aims at identifying unanticipated adverse effects on human health or the environment which could arise directly or indirectly from GM plants. PMEM is composed of case-specific monitoring and general surveillance. Case-specific monitoring is not obligatory but may be required to verify the environmental risk assessment. A general surveillance plan is compulsory and aims at identifying unanticipated adverse effects. General surveillance is not hypothesis-driven but is a general overseeing of the environment making use of existing surveillance systems in addition to developing more focused monitoring systems (e.g., farm questionnaires). Data quality, management and statistical analysis are of high importance in the design of general surveillance plans. Comparison should be made with appropriate baseline data. The EFSA GMO Panel also makes a number of recommendations for the management and conduct of PMEM by both applicants and risk managers.