Abstract: Studies so far have emphasized that mentoring has positive effects on teachers’ academic success, personal and professional development, teaching philosophy, and motivation levels. It has also been reported that mentoring helps teachers perform their roles successfully in their classes and be satisfied with their job. Similarly, many studies indicated that teachers’ self-assessment plays an important role in ensuring the continuity of their professional development. The present study, in turn, builds on the basis of an analysis to identify chemistry teachers’ problems regarding the implementation of the curriculum, and proceeds with mentoring designed to help with these problems. The effects of mentoring on teachers’ capabilities and their teaching behaviors were determined by means of their self-assessments. Four chemistry teachers, teaching in Anatolian high schools in the metropolitan area of a mid-size city located on the north-eastern part of Turkey participated in this study. A self-assessment form (SAF) compatible with the requirements of the chemistry curriculum was developed by the researchers; the final version of the form was revised with reference to the opinions of three science educators. SAF was filled out by the teachers, who participated in weekly mentoring activities, both before and after each mentoring session for eight weeks. The data obtained from SAF was analyzed for each participant as a particular case. It was found that although the teachers assessed themselves as “insufficient” in terms of some items in SAF (regarding existing knowledge and giving examples from daily life etc.) before the mentoring sessions, they rated themselves “sufficient” for the same items after they completed each mentoring session. This change could be regarded as an indicator that teachers have given up some of the negative teaching behaviors and improved their deficiencies through the mentoring sessions. In addition, while some of the participant teachers held overly favorable views of their professional competences, rating themselves “sufficient” or “excellent” with respect to certain items (using performance based assessment and evaluation, employing student-centric teaching perspectives) at the beginning, it was found that they reached to a more realistic assessment of their competence in these themes after the mentoring sessions. One can forcefully argue that mentoring contributes to the participant teachers’ endeavors to get a better grasp of their capabilities. Based on these results, the incorporation of mentoring to teachers’ pre-service and in-service trainings is expected to contribute to the enhancement of the teachers’ competence levels. Considering that Ministry of National Education in Turkey has embarked on a new program in which a prospective teacher (mentee) is mentored by an experienced teacher (mentor) for six months before she/he starts teaching, training the experienced teachers in a such mentoring process wherein faculty members in science education supports them continuously, is expected to bring about a chain reaction to improve teacher competences at all levels.