Genetically modified organisms (GMOs) can have effects on the environment in a variety of ways. The Genetic Engineering Act (GenTG) stipulates that, before a GMO may be used, its characteristics have to be assessed and its behaviour in the environment has to be estimated and evaluated. The Federal Environmental Agency is the first and hitherto only authority involved in the implementation of the Genetic Engineering Act to have presented a risk assessment concept, in order to ensure that consent decisions taken in the enforcement of the Act are comprehensible and comparable. This concept is presented, as are proposals for the envisaged revision which results from changes in the legal framework, notably the adoption of the Biosafety Protocol, the Convention on Biological Diversity and the new EU Deliberate Release Directive 2001/18/EC. In addition, the contribution discusses the role of the precautionary principle and possible implications for decision-making by the authorities. The precautionary principle demands that environmental risks and damage should be avoided as far as possible, or prevented from arising at the outset. A particular challenge when refining assessment concepts is the integration of nature conservation principles. These have been given insufficient attention to date. The contribution presents the results of a workshop on this subject, which was jointly organised by the Federal Environmental Agency and the Federal Nature Conservation Agency. Those participating in the workshop identified aspects which go beyond the scope of the Genetic Engineering Act and are derived from the specific objective of biotope and species protection. Furthermore, the contribution addresses the provisions of the new Deliberate Release Directive 2001/18/EC on environmental risk assessment (e.r.a). The aim of e.r.a., on a case-by-case basis is, to identify and evaluate potential adverse effects of the GMO, either direct and indirect, immediate or delayed, on human health and the environment, which the deliberate release or the placement of GMOs on the market may have. There exists a link to the definition of goals for a sustainable agriculture which have to be considered when assessing the impact of GMOs.