Organizations have attempted to develop Knowledge Management Systems for achieving competitive advantage by effectively managing organizational knowledge. However, if Knowledge Management Systems are not user-oriented, organizations may not attain desired goals. That is, it must be utilized and accepted by organizational members to be successful systems. This study proposes an extended Technology Acceptance Model and empirically validates it. For that purpose, a research model is set UP that consists of antecedent variables, perception moderators, and intention to use the system. Empirical data analysis found significant relationships among research variables, as suggested in research hypotheses. The results of the analysis indicated that perceived usefulness, ease of use, job relevance and information quality should be considered as important factors in designing Knowledge Management Systems. In addition, perceived value, incentive, affect, self-efficacy, and image were found to influence the perception of users in the usage situation.