The concept of personality is frequently used in the field of psychology, but also on a wider scale and is extremely important for understanding human nature. Personality traits affect the impression a person makes on other people, his/her position in relation to others, intensity of his/her desire to achieve his/her goals and the strategy he/she uses to achieve them. Personality therefore doubtlessly affects individual interactions within a social environment. Personality traits are generally considered relevant for work behaviour, affecting individual and group performance and thus the quality of execution of tasks by the team. In the times of fast changes and growing demands for adjustment to new business practices, flexibility is becoming one of the main features of successful businesses. For these reasons, existence of a team organizational structure is perceived as an extremely popular and desirable form of business design. In directing his or her team toward the achievement of goals, a leader uses vision, decisions and procedures to motivate the team members to invest additional efforts to increase the team's performance. Leading a team in this way involves a leadership style, affected by the leader's personality traits. This master’s thesis aims at researching if there is a relationship between leadership style predetermined by the leader's personality traits and the team’s performance and if there is a significant influence of independent variables on the leader’s selection of leadership style and the team's performance. The research has established a relationship between leadership style and the team’s performance.