This paper attempts to explore the nature of the online anti-brand communities in South Korea. The current state of the online anti-brand communities is discovered with regards to different kinds of online platforms and the categories of targeted products and services. Case analyses of three popular anti-brand communities were conducted to discover how dissatisfied consumers form a group, interact with other consumers, and generate group actions. Specific details of consumer interactions and collective actions in the online anti-brand communities provide some managerial implications of how to effectively react to the anti-brand movement. / text