In the bachelor thesis I deal with the influence of stress on work performance. Stress greatly affects the work performance of employees, which is negatively reflected in business development. Each year the company develops new technologies and modernizations are being made. Businesses are changing in the working environment area and are creating new job opportunities, which puts higher demands on employees. In order to maintain efficiency in companies and to enable employees to overcome these changes and to meet new demands, it is necessary to maintain and create working conditions in such a way that they lead to the development of the enterprise and at the same time do not cause too much a burden on the employee. The bachelor thesis consists of three chapters. The theoretical part is devided into two chapters. The first chapter contains general information such as definition of stress, stress types and the impact of stress on humans. In the second chapter I deal with more detailed stress in work environment. The third part contains a research area in which I use questionnaires to find out what extent stress has and how affects employees and their work performance. The main purpose of my work was to clarify the definition of stress, work stress and how stressful are employees and what impact this has on their performance.