This study aims to perform an evaluation of web-based encyclopedia services provided by major Korean search portals, Naver, Yahoo-Korea, Empas, and Daum. These encyclopedia services are evaluated in terms of the relevance, up-to-dateness, and multimedia features of search results. In conducting this study, real queries that real users submitted were used. This study also compares functional characteristics of these encyclopedia services. The results of this study can be implemented to the development and improvement of portal's encyclopedia services. Users can refer to the results of this study in choosing encyclopedia services from search portals.