The aim of this paper is to realise a comprehensive analysis of European corporate governance codes, from the perspective of internal audit, in the manner it is provided in the OECD Principles of corporate governance. The research methodology used a classification of countries by legal regime and the determination of Russel and Rao Similarity Measure, aiming to obtain a global view over the similarity between the European corporate governance codes and the OECD Principles provisions, from internal audit's perspective. The findings suggest that countries from “Former socialists” group are less similar to OECD Principles, from internal audit perspective, while the countries from “French Civil” and “Scandinavian Civil” have a better similarity measure comparing to OECD Principles of corporate governance.