This paper examines what factors influence the performance of congressional members in the Standing Committees and the Congressional Oversight of the 16th Korean National Assembly, It examines five variables such as congressional members' party identity (party in power or in opposition), political experiences (the number of being elected in election and the experience in the local congress), education, age, and the recruiting route(district representation or proportional representation). The author finds that the long experience as a congressman and old age have a detrimental effect on the congressional performance. Doctorate degree holders and female congressional member performed very well. This study compares the performance of congressional members of the 15th Korean National Assembly and draws some implications.