The unauthorized use of a famous brand’s distinctive elements, such as its brand name, slogan, logo, package design, etc., could negatively impact the brand that is imitated (senior brand), through cognitive, affective, or behavioral effects on its consumers (Loken & John, 2010). This phenomenon is called trademark dilution and is defined, in a general sense, as a reduction in brand equity due to the emergence of an imitator or unauthorized user (junior brand) (Simonson, 1993). From a consumer perspective, the brand equity construct cited by Simonson is defined as the perceived added value with which a given brand endows a product, beyond its functional benefits (Aaker, 1991; Farquhar, 1989; Keller, 1993). Simonson (1993) agrees with marketing scholars’ opinion in the sense that brand associations in consumers’ minds are ‘‘key building blocks’’ (p. 151) of brand equity and he explains that, through either weakening or modification of associations, junior brands may dilute senior brands’ equity. Brand equity literature suggests that consumer-based brand equity becomes economic value for the firm through transactions in the marketplace (purchase behavior), recommendations to others, positive word-of-mouth (Keller & Lehmann, 2006) or willingness to pay price premiums (Buil, Martínez, & de Chernatony, 2013). The lack of empirical analysis of brand equity and real purchase decisions in previous studies is considered an important weakness (Magid, Cox, & Cox, 2006; Steckel, Klein, & Schusshein, 2006; Tushnet, 2008); evidence is not provided to ascertain whether there is economic harm for trademark holders. Tushnet (2008), in particular, doubts whether negative effects at the consumer mind level, which include beliefs, attitudes and purchase intentions, are strong enough to reduce purchasing of senior brands. In order to address these gaps in the trademark dilution literature, the main purpose of this study is to analyze the effect that the emergence of junior brands has on real purchase decisions relating to senior brands, mediated by brand equity.