Hazard analysis and critical control point (HACCP) consists of seven principles and is typically described in 12 successive steps. This guidance document provides information on how to validate a HACCP plan and perform verification procedures (Step 11 / Principle 6) to develop an effective HACCP system in accordance with the Codex Alimentarius General Principles of Food Hygiene (CXC 1-1969). Before the HACCP plan can be implemented, it should be validated to confirm that it can ensure consistent control of the significant hazards relevant to the food business under production conditions. Validating the HACCP plan could include a review of the scientific literature, using mathematical models, conducting validation studies, and/or using guidance developed by authoritative sources. After the HACCP system has been implemented, procedures should be established to verify that the HACCP plan is being followed and that it is controlling hazards on an ongoing basis. There should also be procedures to show that the control measures are effectively controlling the hazards as intended. Verification also includes reviewing the adequacy of the HACCP system periodically and when changes occur, as appropriate. This publication is part of the FAO Good Hygiene Practices (GHP) and Hazard Analysis and Critical Control Point (HACCP) Toolbox for Food Safety series. The toolbox is a central repository of practical guidance and resource materials to strengthen food safety capacities, both public and private, in order to develop and implement food safety management programmes in accordance with the Codex standards. Care was taken to consider the challenges faced by small food business operators and primary producers in low- and middle-income countries, and those with an institutional role, such as government officials, academia and capacity building organizations.