The thesis "Performance Management Systems" is divided into two basic units: the theoretical part and the practical part. The theoretical part explains the topic of performance management systems, what they serve, what they look like and what systems models are most commonly used. As part of the system model development, three common methods, namely approaches to performance management, are described: KPI, Six Sigma, and BSC. The practical part of the paper explored whether the implementation of an efficiency management system and in-practice results improved business efficiency of the company on the example of Amazon.com. On the assumption that a profitable enterprise aspires to make a profit and will therefore treat a performance management system as effective if it has a positive effect on the financial performance of the company, it is hypothesized that the implementation of the performance management system may also result in an improvement in the financial position of the company, which can be read from the financial reports. To test the hypothesis, the goal was to analyze the annual financial statements of Amazon.com for a period of eleven years, selected to include three years before the implementation of the performance management system, three implementation years foreseen by analysts and five years after the forecasted completion of the implementation process. The analysis of the financial statements of the company (balance sheet and operating report) for the selected periods revealed that, during the implementation period, the company recorded a significant decrease in business results, total assets and financial returns of shareholders in comparison to the pre-implementation period but these factors improved and established a stable growth in the post implementation period as was predicted by the company analysts. Based on this, it was concluded that the hypothesis is confirmed.