The rapid development of Web technology has resulted in an increasing number of hotel customers sharing their opinionson the hotel services. Effective visual analysis of online customer opinions is needed, as it has a significant impact on buildinga successful business. In this paper, we present OpinionSeer, an interactive visualization system that could visually analyze alarge collection of online hotel customer reviews. The system is built on a new visualization-centric opinion mining technique thatconsiders uncertainty for faithfully modeling and analyzing customer opinions. A new visual representation is developed to conveycustomer opinions by augmenting well-established scatterplots and radial visualization. To provide multiple-level exploration, weintroduce subjective logic to handle and organize subjective opinions with degrees of uncertainty. Several case studies illustrate theeffectiveness and usefulness of OpinionSeer on analyzing relationships among multiple data dimensions and comparing opinionsof different groups. Aside from data on hotel customer feedback, OpinionSeer could also be applied to visually analyze customeropinions on other products or services. © 2006 IEEE.