The purpose of this study is to determine the relationship between the professional values and critical thinking disposition of science-technology and mathematics teachers working in middle schools. The survey research method was employed in the study. The sample of the study is comprised of 193 teachers (90 science-technology and 103 mathematics teachers) working in middle schools located in the city center of Afyonkarahisar, as well as the villages in the same province during the 2013-2014 academic school year. Teachers' Professional Values Scale (TPVS) and California Critical Thinking Disposition Inventory (CCTDI) were used as data gathering tools in the study. The data was analyzed through descriptive statistics, t-test, ANOVA and correlation analyses. The results of the study indicate that the level of teachers' having professional values is higher than middle level and their level of critical thinking disposition is low. Besides, there is a meaningful level of relation between teachers' professional values and critical thinking disposition.