Abstract: Performance appraisal systems (PAS) are required to be effective in order to improve and sustain the employee performance of an organization. Academic staff is considered as the most important stakeholders of a university. Their general objective is to generate knowledge and skills and disseminate them. They hold a very important place in modern society as they directly influence the personal development of the present and successive generations. Evaluation and improvement of PAS for academic staff is a must because success of a university depends on its academia. The main objective of this study is to identify the factors affecting the effectiveness of the existing performance appraisal system for academic staff of General Sir John Kotelawala Defence University (KDU).