Of the many approaches to building a brand’s image on the Internet, a Web site is one of the most important tools for managers. An important decision made by Web site managers is whether to place banner advertisements on their brand’s Web site (e.g. The New Yorker Web site placing an ad for polo.com). While banner advertisements are widespread in the marketplace, it is unclear whether Web sites containing such advertisements may be harming themselves by such a practice. This study addresses this issue by investigating the impact of banner advertisement and Web site congruity on consumer attitudes toward a brand’s Web site. The results of an experiment indicate that if managers include such advertisements on their Web site, these advertisements should be consistent with the Web site brand and that certain consumer characteristics should be considered. Implications of the research for brand management and advertising on the Internet are provided.