The aim of the article is to present the insights of carried survey on evaluating the level of significance of managerial competencies in comprehensive schools in Lithuania. The approach that head teachers' managerial competency highly influences the process of education and is one of the most important factors ensuring efficiency of school activities such as educational policy and strategic planning, educational process, management of human, material and financial resources has been followed. Researcher self-made questionnaire for expert evaluation was used to measure competency components. In the paper the author presents main results of one part of the research related to school leader's competencies in management area, which was divided into five spheres: strategic institution management, teaching and learning process administration, managing human resource development, ensuring and managing structure, processes and resources of institution, strategic partnership and collaboration. Each of the spheres comprises different items - competences a successful headmaster should dispose. The significance, specified as the most important, was assessed by ranking procedure. The Kendall coefficient of concordance has been used to assess the agreement among raters for every ranked question. The results revealed that the most significant head teachers' competencies which highly influence the results of school activity areas are the abilities to form the strategic direction and implement effective staff policy, strengthen the attitude of school community that each student can reach a success in the learning process, organize conducive conditions for professional staff development, administer property and allocations, collaborate with parents, foster-parents or guardians.