It has been contended that companies must move from satisfying their customers to delighting them (Rust, Zahorik and Keiningham 1996). It has also been observed that features that can be used to delight are those that are "surprisingly pleasant" (Rust and Oliver 2000: p.87). Many relationship marketing activities are being copied and therefore fail to provide for a long-term strategic advantage to the companies that originally launched them. Moreover, some of such activities do not work as originally intended. This article examines when and how surprise can be applied as a marketing tool in retaining a company's customers. A review of the existing literature on (1) the use of relationship-based marketing and emotion-based marketing and (2) the emotion of surprise suggests that it is close to impossible for a company to copy emotion-based marketing activities. Interestingly, the emotion of surprise has recently been proposed as being appropriate for emotion-based relationship marketing. This article argues that surprise can be an extremely efficient marketing tool, but that marketers need to be aware that some situations are more suited for using surprise than other situations. In order to reach this conclusion the article reviews empirical research on the emotion of surprise and its influence on marketing variables such as customer satisfaction, customer retention and trust.