Branding makes distinct difference between one or more products among other products. Brand equity is considered as collected marketing investments of a brand and also an element of brand success which might be affected by any marketing action. Customers are forming relationship not only with a brand but also with other customers of the brand; with the help of internet customers form ‘brand communities’ or ‘anti-brand communities’. Anti-brand communities reflect negative perceptions of the brand. In addition to that, social media such as anti-brand websites motivate dissatisfied customers to express themselves. Even a small mistake can be spread fast among customers, which in turn could bring consequences for the company such as loss of loyal customers or negative change in customers’ perceptions of their product. Hence, the impact of customers’ ideas and the word-of-mouth on brand equity is undeniable, and the effect of online word-of-mouth is therefore a significant issue to study.The purpose of this study was to increase the knowledge about the influence of anti-brand websites on customer-based brand equity to determine how the influence of anti-brand websites can be characterized. The effect of anti-brand websites on four factors (e.g., brand awareness, brand personality, perceived quality and brand loyalty)was studied in this thesis.A qualitative and deductive approach was adopted and two cases namely Starbuck and Coca Cola, and their respective anti-brand website (starsucks.com and killercoke.org) were studied. . Data was collected through individual, in-depth, interviews with respondents having experience of using the case brands. Results suggest that anti-brand websites can increase the awareness of the brand by rising the issues and discussions although it raise the awareness negatively. However, the results indicate that anti-brand websites do not play any noticeable or highlighted role on perceived quality of the brand.Surprisingly, brand associations were altered both negatively and positively by the influence of the anti-brand websites, while these websites do not seem to have any considerable effect on brand loyalty This study recommend that for those brands seeking to keep track of customers and want to keep their position in market, it would be useful to find the factors driving negative sentiments. Once it is understood; the company strategies can be applied to reduce such negative sentiments and prevent any negative tipping point besides using anti-brand websites as a marketing tool.