This paper analyzes the method of conducting an internal audit using the ISO9001 standard. Internal audit aims to identify deficiencies in the implementation of processes and internal control so that they can be corrected as quickly as possible in order to reduce the damage caused to the company or its participants. Accordingly, an internal audit plan for an organization should be risk-based, or in other words, designed to examine those areas that pose the greatest risk to the company. The internal audit plan should also include a component of the organization's strategic needs. After conducting the audit, internal audit reports are drawn up. Reports can be carried out in different ways, which depends on the subject of the audit and the type of production. After the internal audit, a report is drawn up that contains all the relevant data collected during the audit, on the basis of which it is determined whether there are non-conformities. The report must include all data on the internal audit, all the findings of the internal audit and all non-conformities found. Nonconformities that are found are resolved according to the procedures defined by the organization's quality management system. On the basis of the obtained results, activities are carried out with the aim of eliminating disagreements, and after that an evaluation of the effectiveness of the implemented remedial activities is carried out. The internal audit is carried out until all observed non-conformities are eliminated.