Leadership and leadership style were considered to be of great importance and were analyzed over time from different perspectives. In process of defining leadership style, there have appeared several problems in specialized literature. One of these problems is related to the fact that some authors propose to operate a distinction between "type of leadership" and the "style of leadership". A second difficulty stems from the different attitudes of the authors towards to the content of leadership style. Leadership can be defined as a set of typical procedures, a special form of influence over the team in order to effectively fulfill the administrative functions and tasks facing the government body, a special form of personal thinking, behavior and action of leader. The importance of leadership style in the institution comes from the effects over the psychological, psychosocial and relationship environment of headed units; high capacity of diffusion among group members; capacity to target the work of entire leadership team; related action of leadership style and others variables. Currently, the specialized literature outlines a large number of classifications of leadership styles that could be grouped by the number of criteria that underlie them. Thus, there exist one-dimensional, two dimensional and three dimensional types. Leadership style influences organization in several directions: the level of labor and intellectual productivity of headed group, psychosocial relationships within the group, attitudes of group members, group cohesion, motivation of subordinates' behavior, the personal satisfaction of group members. The studies conducted in the Republic of Moldova and in other countries had shown that leadership styles have not just one category of effects. Improving the positive effects of leadership style over the organization is a major concern of leadership theory and practice.