My thesis is divided into two main parts, such as the theoretical and practical part. In theoretical part, I describe brief history of Internal Audit with the special interest on the Czech Republic and Sweden. I mention these two countries as the headquarters of Skanska are found in Sweden and it has a long developed tradition. Then, I concentrate more on IA organization and procedures, IA standards and code of ethics. Furthermore, I concentrate on the methodology used in IA. In practical part, I focus more on a description of IA process at Skanska. I describe the practical background of this company and later on, I have mentioned two practical cases targeted on audit of one loss project and audit of processes such as Accounts payable and A...