Although the relationships with sports fans is one of the most important distinctions between professional sports and other businesses, the concept of relationship building has not heavily emphasized in the sport industry. Bovinet (1999) indicated the potential problems happening in professional sports management and marketing were maintaining customer relationships, building customer databases, and developing customer services. He suggested the current professional sport organization needed to communicate more effectively with customers. In addition, the advent of the Internet has created a direct link between customers and companies that help customers speak directly to marketers about their needs and wants. Therefore, customer relationship management combined with Internet technology has become an important marketing approach for sport organizations that want to be successful in this highly competitive sport industry. The purpose of this study was to examine online relationship building of the selected 13 professional sports leagues through a content analysis. In this research, there were 5 key steps involved in the process of conducting content analysis: (1) formulating research questions or hypotheses; (2) selecting a sample; (3) defining categories; (4) developing coding content, training coders, and checking coding reliability; (5) collecting, analyzing and interpreting research data (Budd, Thorp, & Donohew, 1967; Krippendorff , 1981). The instrument developed for this study was based on Feather's "10 Cs" of Website Marketing (Feather, 2000), which was modified by the researcher and became the "12 Cs" of Web Sport Marketing with 58 coding units. Descriptive statistics and frequency distribution tables were provided to describe and summarize the large mass of data that was collected. The results of this study indicated that only 52.38% of the12 key strategic elements with 58 coding units were frequently used by the 13 selected professional sport league/organization websites, which was just slightly above half of them. The most frequently used of the “12 Cs” of Web Sport Marketing was Confidence (88.5%), Communication (71.8%), and Content (65.4%), yet Connectivity of Fans (15.4%), Choice (23.1%) and Customization (23.1%) were the least frequently used elements. Furthermore, the most frequently used of information to build their customer relationship among the selected 13 professional sport league/organization websites was Web-based Sport Media Information (60%), followed by Value-added Services (52.9%), Interactive Communication (51.3%), and Convenience (42.3%). An overall difference was found in this study, which showed that differing online information was applied among the selected 13 professional sport leagues/organizations to build their relationships with fans and customers.