This study empirically examines the relationship between the role of R&D project leaders and their team performance using data from 87 project teams in 6 R&D organizations in Korea. The results reveal that: (1) R&D project leaders played five different roles in performing their jobs - strategic planner, team builder, gatekeeper, technical expert, and champion; (2) AU but the champion role of a leader is positively related with project team performance; (3) However, this relationship between the role of leader and project team performance varies according to the characteristics of R&D project teams and their tasks. Specifically, it becomes important for a leader to focus less on the team building role as the team gets older. The team building role of a leader, however, is more important for higher performance of relatively certain R&D projects, while for uncertain R&D projects, the strategic planning rob appears to be more crucial. Based on these results, this study discusses several managerial and theoretical issues related to the role of a leader in R&D project teams.