This study assessed the roles of performance review on improving Public Services in Public Services Commission of Zanzibar. The objectives of the study were; to explore the factor that contributes to the assessment of employees in public sectors. To explore the methods used in employees’ assessment process in public service commission, to explore the benefits of assessment of employees to achieving organizational goals in public service commission. The study was conducted using a case study research design; hence a qualitative research approach was used. The study population involved 42 staffs of the Office of Zanzibar Public Services Commission which is located at Mwanakwerekwe Zanzibar. The study involved 20 respondents as sample. A purposive sampling technique was used to obtain study sample and semi structured interview was used as a data collection method, while a content data analysis was used as qualitative data analysis method. The findings of the study indicated that performance review in public service Commission are affected by business factors, Government Regulations, Time factors and Performance Standard. Management by Objective, Competence base, Fairness of the Assessment, Participatory approach and Feedback are the major methods of Performance review in Public Service Commission. Basing on these findings, the researcher recommended that; Performance review should be conducted on the right time in order to provide the opportunity for the employees to get their rights. Knowledge should be provided to the employees and also management concerning the importance of conducting performance review. The government through the Office of Zanzibar Labor Commission should ensure all public offices are conducting performance review