Designed and synthesized were a series of pyridines substituted at 2, 4, and 6 positions with various 5- or 6-memberd heteroaromatics as antitumor agents. They were evaluated their topoisomerase I and II inhibitory activities along with cytotoxicities against several human cancer cell lines. Among the prepared compounds, 10-20 showed significant topoisomerase I or II inhibitory activities, and 21-26 showed considerable cytotoxicities against several human cancer cell lines. Structure-activity relationship study indicates that 4'-pyridine at 6-position of central pyridine plays a key role in biological activity.