The aim of this study is to investigate the transformational and transactional leadership styles of school principals, and to evaluate them in terms of educational administration. Descriptive survey model was used in the research. The data of the research were obtained from a total of 1,117 teachers working in public and private schools subjected to ministry of national education in Avcilar district of Istanbul province in 2014. In this study, data were obtained from the "personal information form" developed by the researcher and from the "leadership styles scale". Data entry that was obtained from the respondents was made by statistical package for the social sciences (SPSS) version 17.0, and research data was resolved with "average", "standard deviation", "t-test" and "one-way analysis of variance". According to research result; teachers had a high level of positive opinions with regard to transformational and transactional leadership characteristics of school principals. Teachers' perceptions about transformational and transactional leadership characteristics of school principals did not vary significantly according to gender, state of education and professional seniority.