Dissertation (MA Public Administration)The study was conducted in Zanzibar at ZECO to investigate the factors influencing implementation of performance appraisal system in public organization. The literature review that Performance appraisal system was introduced in July 2004 and was implemented for a minimum of three years all over the country, to all central and local agencies of the government. However, little change can be seen judging by the services delivered by the public sector. From the field data collection was carried out using structured questionnaires, interview and observation checklist guide in the office whereby the workers were selected purposively and randomly. A total of 140 workers at ZECO were interviewed. Analysis of both primary and secondary data was done using Ms Excel and SPSS. Results indicated that ZECO was still using Closed Annual Confidential Report System instead of OPRAS. Despite the use of CACRS still the performance was in average, which was not bad or good. The workers were still working fairly not perfectly. It was indicated that CACRS was successfully implemented as it was cited by 67% of all respondents. Different impacts from performance appraisal were identified such as improvement of public services delivery, organization to assess the individual employees, increase of team work and the like. However, different challenges were identified that led to ineffective implementation of performance appraisal. Finally, different solutions were given out by respondents; it is believed that if well implemented by the government may lead to effective implementation of performance appraisal. In addition, the provision of seminars to workers about the system, proper documentation of feedback from workers, operate regular evaluation and analysis of the results from the system, proper communication to all managers and supervisors.