Web site owners have trouble identifying customer purchasing patterns from their Web logs because the two aren't directly related. Thus, organizations must understand their customers' behavior, preferences, and future needs. This imperative leads many companies to develop a great many e-service systems for data collection and analysis. Web mining is a popular technique for analyzing visitor activities in e-service systems. It mainly includes Web text mining, Web structure mining and Web log mining. Our Web log mining approach classifies a particular site's visitors into different groups on the basis of their purchase interest.