This paper outlines an approach to a science-based risk assessment for transgenic plants intended for use in agricultural and other managed environments.  The assessment, which focuses on the product rather than the process, concerns the possible risks due to gene transfer, weediness, trait effects, genetic and phenotypic variability, and expression of genetic material from pathogens, bearing in mind worker safety.  This risk assessment is applied in the light of the impact of conventional agriculture on the environment, risk management and the balance between risks and benefits.