One of the purposes of the joint REN and FAP task, Environmental Problems of Agriculture, is to collect, assess and classify the current agricultural-environmental models. In order to obtain information and establish scientific cooperation, special questionnaires were sent to many scientists in various countries. This paper contains a brief description, assessment and classification of twelve nitrogen leaching models, and a list of scientists contacted. The nitrogen leaching models can be used for solving some environmental problems related to the application of nitrogen fertilizers.