In this paper, the concepts of internal and external audit will be analyzed and their purpose, characteristics and phases and the processes that take place within them will be more clearly presented. Likewise, the term audit will be briefly analyzed in order to make it easier to understand its division into internal and external. Developing a topic will analyze the cooperation of internal and external audit. For the purposes of this analysis, their main differences will be outlined, as well as how they get coordinated through audit planning, exchange of reports, discussion of common issues, and process statements. Also, internal and external audit cooperation according to International Standards on Auditing will be shown. At the very end of the paper, the International Auditing Standard (MREV 610) will be presented, outlining its scope, purpose and scope of decision making, followed by the conclusion of the paper.