It has been well recognized that vendors’ reputation plays an important role in e-commerce. As a popular platform for promoting the services or products online, groupon websites have developed various reputation systems to assist the customers in making their purchase decisions. This paper performs an empirical study to investigate the impact of service reputation on the groupon buying behaviors using data from a major groupon website in China. A set of service reputation metrics is developed to measure the service reputation for different service providers, and the groupon buying behavior is measured by the amount of users participating in the corresponding collective buying activity. Correlation analysis is carried out to find out the relationship between the service reputation and the groupon purchase behaviors. Our research indicates the necessity for an improvement for the current service reputation systems of the groupon web sites.