Abstract: In order to be successful the companies shall identify the factors that affect its efficiency and effectiveness. Internal audit could be useful tool in that process since its purpose is collecting the evidence and evaluating it objectively to determine the extent to which audit criteria are fulfilled. In other words, internal audit can be used to evaluate the extent to which planned activities are realized and planned results are achieved. The process of conducting the internal audit is described in standard ISO 19011, however its realization depends only upon the company itself and its concepts of internal audit.