The 20 key methodology is just one of the many tools to improve business operations. With a growing importance, many companies apply these tools in order to create competitive advantage. Nevertheless, the main emphasis is placed on the 20 keys methodology and its successful implementation on the example of two Croatian corporations, one of which is a service and another production company. The research is carried out using the descriptive method by which the results of the research are presented and they point to the successful implementation of the methodology. The objectives of this paper are to theoretically define contemporary improvement systems with an emphasis on the 20 key methodology and the implementation of methodology in practice. Although the 20 key methodology results are not considered statistically relevant due to the accompanying documentation (control list), it ultimately has the greatest impact on business within the organization. However, by continuous use, the future can lead to improved business results in financial statements. The research shows the success of applying the 20 key methodology, which has led to reorganization and further using in corporations, which confirms the wide implementation in the Republic of Croatia as well as in other countries.