This report is the first one of a series in which the methodology for hazards/risk assessment of the use of pesticides for birds and mammals will be presented. After a general introduction a synopsis of the developments of the last 10 years has been given. The presented hazard/risk assessment scheme is a compilation of all decision scheme concerning birds and mammals up to now in the Netherlands and consists of 5 modules. In modele A one is lead stepwise by way of yes/no questions to the module that is applicable to the mode of use of a particular pesticide. In module B the exposure by granules, treated seeds, slug pellet or baits for rodents is considered. Module C deals with the exposure by pesticides used for spraying crops/plants and/or insects, module D with exposure by drinking water and module E with secondary poisoning. Exposure routes like inhalation or contact and other secondary poisoning pathways will be incorporated into the scheme as soon as available. Furthermore, attention has been givin to the considerations for the use of particular cutoff criteria and a description of the terms used in the scheme has been given.