As Internet and computers become widespread, health portals offering online health-related information become more popular. The most important point for health portals is presenting reliable and valid information. Besides, portal needs to be usable to be able to serve information to users effectively. This study aims to determine usability issues emerging when health-related information is searched on a health portal. User-based usability tests are conducted and eye movement analyses are used in addition to traditional performance measures. Results revealed that users prefer systematic, simple and consistent designs offering interactive tools. Moreover, content and partitions needs to be shaped according to the medical knowledge of target users.