We investigate the effect of search engine brand (i.e., the identifying name or logo that distinguishes a product from its competitors) on evaluation of system performance. This research is motivated by the large amount of search traffic directed to a handful of Web search engines, even though most are of equal technical quality with similar interfaces. We conducted a laboratory study with 32 participants to measure the effect of four search engine brands while controlling for the quality of search engine results. There was a 25% difference between the most highly rated search engine and the lowest using average relevance ratings, even though search engine results were identical in both content and presentation. Qualitative analysis suggests branding affects user views of popularity, trust and specialization. We discuss implications for search engine marketing and the design of search engine quality studies.