Excerpts from the Executive Summary: In June 1990, the National Agricultural Pesticide Impact Assessment Program (NAPIAP) began an assessment of phorate and terbufos usage in U.S. agriculture. The results of the NAPIAP assessment have been published in this report so that the U.S. Environmental Protection Agency (EPA) will have an overview of the benefits of phorate and terbufos use to U.S. agriculture. This report was prepared by a team of scientists from the U.S. Department of Agriculture and State Land-Grant Universities to provide sound, current scientific information on the benefits of phorate and terbufos to U.S. agriculture. The scope of the report has been limited to an evaluation of the economic benefits to U.S. agriculture which are obtained from the use of these insecticides, and the economic impacts that would likely occur should their use be canceled by Federal regulations. Because the health and environmental impacts associated with the use of these insecticides will be evaluated by EPA, these aspects have been discussed in this report only as they relate to U.S. agriculture. The economic impact on producers and consumers of agricultural products in the United States caused by the cancellation of phorate would be an annual loss of $21 million (Table 1). Corn and potato producers would sustain the greatest economic loss if phorate is no longer available. The economic impact caused by the cancellation of terbufos would be $127 million, including a loss of $118 million to corn producers and consumers. The aggregate economic effect on producers and consumers caused by the cancellation of both phorate and terbufos would be an annual loss of $168 million.