This study aims to discuss Regulatory Impact Analysis (RIA) in Brazil focusing on policies for agriculture and livestock defense. The main concepts and analytical tools were presented, and the Cost-Benefit Analysis (CBA) was highlighted as the most recommended by policy makers for RIA. To illustrate the application of this method in programs for agriculture defense, we discuss three case studies which were carried out in Brazil: Carambola fruit fly in Amapá State, Huanglongbing (greening) and citrus canker. The results show that the benefits surpassed the costs in these programs, particularly from the government point of view. Besides, when the analysis for citrus canker took into consideration the private costs, there were scenarios in which these costs were not offset by the economic benefits. Although the CBA allows identifying and comparing returns for different policy alternatives, the environmental and social aspects are usually poorly captured by this tool.