The annual incidence of microbiological food borne disease in the United States ranges between 6.5 million to 33 million cases with as high as 9,000 deaths. There is a developing consensus that the Hazard Analysis and Critical Control Point (HACCP) concept is the most effective and rational means of assuring food safety from harvest to consumption. The first step in the application of the HACCP concept involves conducting a hazard analysis. It is essential that this procedure is performed correctly, because the subsequent plan and procedures developed to control the identified hazards are based on this critical first step. Recently the National Advisory Committee on Microbiological Criteria for Foods (NACMCF) and Codex Alimentarius have published information on HACCP principles and application, but have not provided a comprehensive method for conducting a hazard analysis. Guidance on hazard analysis issues such as the determination of significant hazards for inclusion in a HACCP plan, the probability of occurrence (risk), and hazard severity is lacking. Practical guidance for conducting a hazard analysis and applying Principle #1 was developed. A decision tree approach is proposed that provides a logical framework for deciding what hazards are to be included in the HACCP plan and thus controlled in the food process. Additionally, guidance on what considerations and information are required at each level of the decision tree is provided. These decision trees and accompanying information provide a practical and uniform basis for applying Principle #1 and determining which hazards should be addressed in a HACCP plan. The use of risk assessment as a part of risk analysis is also gaining increasing popularity as a means to prioritize food safety issues and policy. Some have proposed the incorporation of risk assessment within the HACCP concept. The relationship of risk analysis to hazard analysis and justification for keeping the two procedures separate is discussed. The methods used in risk assessment and HACCP are at times Similar, but should not be considered the same. Risk assessment and HACCP are two separate functions with two separate scopes, and the incorporation of risk assessment into hazard analysis at this time is counterproductive and should be discouraged.Ph. D.