The aim of this study is to determine the relationship between the favouritism behaviours of secondary school administrators and organizational commitment of teachers. The research population consists of 3403 teachers from 64 secondary schools in the central district of Diyarbakir/Turkey in the academic year of 2016-2017. The data collection instrument was applied to randomly selected 376 teachers from 22 schools. "Favoutism in the School Management Scale", developed by Erdem and Meric (2012) and three dimensional "Organizational Commitment Scale", developed by Meyer, Allen and Smith (1993) and adapted into Turkish by Dagli, Elçiçek and Han (2017) were used in this research. The arithmetic mean, standard deviation were used in the analysis of data. The relationship between favoritism and organizational commitment behaviour was studied using Spearman Correlation Coefficient. Some important findings obtained in the research can be listed as follows: Teachers participated the overall mean of "Favouritism in the School Management Scale" at "sometimes" level (M=2.86). According to teachers' perceptions, the dimensions with the highest means are in order; (1) Planning (M=3,121; Sometimes), (2) Coordination (M=2,961; Sometimes), (3) Evaluation (M=2, 368; Sometimes) and (4) Organization (M=2,936; Sometimes). Teachers participated the overall mean of "Organizational Commitment Scale" at "not sure" level. According to teachers' perceptions, the dimensions with the highest means related to organizational commitment are in order; (1) Affective commitment (M=3,07; Neutral), (2) Continuance Commitment (M=2,79; Neutral) and (3) Normative Commitment (M= 2,63; Neutral). In the study, a moderate level of negatively significant relationship was found between favouritism behaviours of school administrators and organizational commitment of teachers. (r=-0.359, p < 0.01). The more favouritism behaviours of school administrators are, the less organizatioal commitment of teachers are.