• Post Market Environmental Monitoring (PMEM) is mandatory in all applications for deliberate release submitted under Directive 2001/18/EC and EU Regulation 1829/2003. • PMEM aims at identifying possible 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 (CSM) and general surveillance (GS). CSM is notmandatory butmaybe required to verify the environmental risk assessment while GS must be part of an application. • EFSA is responsible for assessing the scientific quality of PMEM plans submitted with each application. • EFSA has adopted guidance to applicants for developing PMEM plans (adopted December 2005). • The EFSA GMO Panel is of the opinion that GS cannot be driven by specific hypotheses (cause-effect) and should, when possible, make use of existing monitoring programmes in addition tomore focussedmonitoring systems as farm questionnaires. • Data quality, management and statistical analysis are of high importance in the design of a GS plan and comparison should be made with baseline data. • EFSA recommends early contact between applicants and Member States (selection of existing networks) and recommends harmonisation and coordination of data collection and analysis. • PMEM is a risk management measure. • The Commission and the Member States via their Competent Authorities are responsible for the PMEM and take the decisions. • The body in charge of proposing harmonisation of PMEM is the EU Monitoring Working Group. • A pragmatic PMEM for MON 810 that addresses the proposedprotectiongoals has been implemented successfully. • The 2005 monitoring report for MON 810 confirms the conclusion of safety reached in the environmental risk assessment. • The future presence of multiple events and stacks on the market will require: – some adaptation, including modularity, – a harmonised approach across the industry that has started under the EuropaBio banner.