The subject of this thesis are global standards of financial reporting, harmonization process and their impact on the financial statements of multinational companies. The intensified process of globalization in the 21st century has created the need to develop global financial reporting standards to increase the comparability and accuracy of financial statements. International Financial Reporting Standards are predominantly used in the preparation of financial statements of companies operating in several different countries. Also, American generally accepted accounting principles are used but they are more common in America. Given that there are numerous differences between the two standard standards, new ways are constantly being sought to eliminate or minimize significant differences between the standards. The IASB and FASB are making efforts to increase the compatibility of accounting practices within the harmonization process. Harmonization has several positive effects on global financial reporting that have an impact not only on accountants who prepare financial statements but also on companies (the reporting entity) and the users of the reports themselves. In this paper, the concepts of multinational companies and international accounting are explained in more detail. The general principles, significant global standards of financial reporting as well as the concept of harmonization are stated and described. Also, the differences that represent obstacles in the harmonization process as well as the positive effects that this process brings have been identified. Finally, the specific financial statements of three companies operating in the same industry but located in different parts of the world were analyzed.