This paper employs citation analysis to investigate empirically the influence of top IS journals on both IS and other literature. We assessed the quality of the three top IS journals by comparing their citation indices and examining the distribution of their citations among different disciplines. Some 7429 citations from the Social Science Citation Index and Social Science Index (2003-2009) are made to 425 source articles published in MISQ, ISR, and JMIS between 2003 and 2007 (inclusive). Our results reveal that the citation-based quality indices of MISQ are consistently better than those of ISR and JMIS. In addition, our results provide strong evidence that articles published in the three top IS journals have significant impacts to different disciplines, with JMIS appealing most to articles in science and engineering and ISR contributing mostly to professional journals and magazines. The knowledge contribution of MISQ appears to be the most balanced among the three.