The guideline VDI 4330 Part 1 applies to the monitoring of ecological effects of genetically modified plants (GMPs) and does not address possible effects of GMPs on the human health. It provides planning and implementation criteria for environmental surveillance and forms the framework for technical instructions. The guideline describes from the technical point of view items to be protected, protection targets and checkpoints that have to be taken into account when monitoring possible ecological effects of GMPs. Furthermore, criteria for the selection of methods and monitoring areas are formulated and requirements regarding quality assurance and data management are stated.