In this report a risk assessment or evaluation system for agricultural pesticides is presented, which estimates the hazards for man and environment resulting from the use of these pesticides. The evaluation system has also been placed within the context of the Uniform System for the Evaluation of Substances (USES). The evaluation system for pesticides (ESPE) is divided in three parts: 1) emission of the pesticide ; 2) distribution over and within the different environmental compartments and calculation of exposure concentrations of organisms to the pesticide ; 3) hazard assessment. The mathematical descriptions of various parts of the assessment system for agricultural pesticides are presented in this report. In the first part, an estimation is made of the percentages of emission of the used dosage for the several environmental compartments. In the distribution part, the different transport and translation processes are assessed. This leads to Predicted (Initial) Environmental Concentrations (P(I)ECs) for the different environmental compartments and to transport fluxes between these compartments. In the third part, hazard assessment is carried out by comparing P(I)ECs with chronic or acute toxicity data (e.g. NOECs,L(E)C50s) for several non-target organisms. For the environmental hazard assessment decision trees, developed by the Support Group Environment of the CTB, are used. For human beings, in this system only consumers, no decision trees have been developed. Hazard assessment for indirect exposure is performed by comparing the total daily intake with the No Observed Adverse Effect Level (NOAEL).