From the long-term branding perspective, this study examined the effects of ad rankings in search engine result pages on memory and evaluations, particularly for unknown brands. Subjects' topic knowledge (TK) and persuasion knowledge (PK) about keyword search ads were examined as moderators. Holding click-through rates constant, the results of an experiment, in general, suggest that top-ranked keyword search ads for the unknown brand may generate greater recognition and more favorable brand evaluations along the primed attribute than ones ranked lower than well-known brands. Online users' TK and PK about keyword search ads are working together to enhance or attenuate such ranking effects on brand recognition and evaluations. Theoretical and practical implications of these findings are discussed.