© 2019 Uniwersytet Pedagogiczny. All rights reserved.In this study, it was aimed to investigate the beliefs of mathematics teachers about mathematics instruction and their teaching selfefficacy within the scope of flow theory. Participants consists of a total of 228 mathematics teachers engaged in teaching at secondary and high school levels in Turkey; they were determined using the combinations of convenience and purposive sampling. Data from the participants were obtained using The WOrk-reLated Flow inventory (Wolf), The Ohio State Teacher Efficacy Scale (OSTES) and Mathematics Related Belief Scale (MRBS). Results revealed significant positive correlations among Constructivist Beliefs of Wolf, OSTES and MRBS. Furthermore, it was found that mathematics teachers graduated from the Education Faculty had higher MRBS Constructivist Beliefs that the ones graduated from Faculty of Arts and Sciences.