An audit is used to verify and ensure that the processes and methods used in a clinical laboratory comply with the required standards and to continuously improve the service provided to service users. The International Organization for Standardization – ISO9001 – defines an audit as “A systematic and independent examination of whether quality activities and their results comply with planned arrangements and whether such arrangements are implemented effectively and are suitable for achieving the objectives” .1 Audits are therefore an essential part of the Quality Management System and are a requirement of Clinical Pathology Accreditation (CPA). The purpose of an audit is to gather information through observation, discussions and sampling to recognize areas where improvements can or should be made to improve laboratory standards. An audit doesn't just identify the poorest processes in the lab, it also identifies those that work well, giving staff the opportunity to learn from good practice and allow knowledge to be transferred to other processes. The audit allows organizations to evaluate their methods, determine any problems and produce efficient and cost-effective solutions to resolve them. Audits are used to check practices against procedures and to carefully document any differences that may occur in detail. However, audits are only sampling exercises, so they cannot confirm that all aspects of a method are adhered to at all times. There are 4 main types of audits:1. Vertical audit ...... half of the document ...... or identify any problems in the quality management system and suggest any actions to be taken to improve the laboratory system. An external audit is conducted by an external person or organisation, such as the CPA and Health and Safety Officer of the NHSGG&C (biochemistry), MHRA and UKAS (haematology) and the Health and Safety Officer of the NHSGG&C (microbiology). These bodies want to ensure that laboratories follow and comply with standards and provide a safe and effective working environment. An external horizontal audit is conducted by an external person on a specific item such as staff skills records. On the other hand, a cooperative audit is carried out between the laboratory and another mutually beneficial party, such as department staff or clinic staff. These audits usually consist of clinical audits or user satisfaction questionnaires.