In this study, we evaluated web usability for hospital web sites in Korea and analyzed the evaluation results of web usability. Estimators investigated twelve hospital web sites and answered a questionnaire. They also performed predefined tasks which were frequently used services in hospital web sites. We had an interview with the estimator for finding what happened in process of evaluating usability. The evaluation results showed that university hospital provided comparatively better web usability for users. But ambiguous and complicated user interface caused confusion among users. The simplifications of service processes and interfaces were necessary to improve web usability. Some hospitals did not offer primary web services and their services related to the tasks were not systematic.