Assessing the potential environmental impact of alien plants and plant pests is notoriously difficult. New protocols have been developed in the framework of the EC project PRATIQUE to provide guidance on environmental impact assessment in the EPPO pest risk analysis (PRA) decision-support scheme and enhance consistency between risk assessors and risk ratings for different pests. A set of questions with rating guidance and examples is provided, and individual scores are summarized into final scores, using a hierarchy of risk matrices, to assess current and potential environmental impacts. Two separate protocols are available: for alien plants and for other pests. These protocols could also be used to assess environmental impact in other PRA schemes as well as to assign alien species to regional black lists or to prioritize species for management decisions.