The study was conducted at Ilemela district in Mwanza City between February to June, 2015. The study examined the impact of open performance review and appraisal system on improving teachers’ teaching in Public Secondary Schools in Ilemela district. The study was based on three specific objectives; teachers’ perceptions on open performance review and appraisal system in education system, contributions of open performance review and appraisal system on improving teachers’ teaching professional, and suggestions for improving open performance review and appraisal system in public secondary schools. The goal setting theory by ‘Locke’ was the only theory was involved in this study. Mixed research approach in data collection through quantitative and qualitative was used in this study. Simple random sampling was applied to obtain 7 secondary schools and 125 teachers as respondents who were required, while purposive sampling technique was also employed to obtain information from 7 schools heads and 1 district secondary education officer. Explanatory design was used in the study, where data were collected through questionnaires and semi- structured interview, and reviewing documents. The study found that, OPRAS was done without pre-preparation, and was fruitless practice to teachers’ professional growth. Education officers did not provide feedbacks to teachers. Teachers filled OPRAS forms without adequate knowledge, teaching and learning environment was poor to exercise OPRAS practices. Furthermore, provision of trainings to heads of schools, classroom teachers, and enough funds to schools were required. Moreover, Education Officers should provide feedbacks to teachers and further measures to be taken. School heads should be trained adequately on how to conduct OPRAS, and results of OPRAS should be used for teachers’ promotion, salary increment and punishment. The government should support secondary school adequately in financial issues. Therefore, success of OPRAS could be achieved through solving number of challenges facing all members are involved.