To ensure that all appropriate measures are taken to avoid adverse effects on human health and the environment that might arise from the contained use of genetically modified and/or pathogenic organisms, an risk assessment is carried out as regards to the biological risks. While classification list of pathogenic, non genetically modified, organisms provide a tool to assess the biological risks associated to the contained use of those organisms, the risk assessment of GMO appear to be more complex. This document provides a practical means for performing risk assessment of contained uses dealing with genetically modified organisms (GMOs), whether they are pathogenic or not. The first part offers a brief summary of the key issues of risk assessment of contained uses. The second part (annexes) consist of examples that have been elaborated to illustrate the risk assessment of contained uses dealing with GMOs.