Knowledge Management System (KMS) is a necessary concept as knowledge possessed by each individual employee is an intellectual property asset that will provide benefits for any organization. In a company, in terms of KMS, employees’ performance holds an important role in helping run the business of the company becoming sustainable and successful. Therefore, the measurement of employees’ performance based on a balanced scorecard is needed to understand the current business situation. This research helped focus on the perception between the KMS and employee’s performance based on a balanced scorecard (BSC) regarding a financial perspective, customer perspective, internal business process perspective, and learning & growth perspective. A survey was conducted at PT. Vale Indonesia Tbk (Vale) to ascertain these perspectives and perceptions of employees regarding performance based on a BSC. These perception data were analyzed, and conclusions were drawn regarding hypotheses. The findings section of this thesis shows the results in details. The results of the survey showed that the employees had a good perception of the value and benefits of KMS as measured with the BSC with the exception of the financial aspect. The interpretation of the results created recommendations to further implement KMS, and to improve employees’ performance at Vale.