We investigated how patients use a symptom selection tool developed for use within Web-CHOICE, an Internet-based support system for cancer patients. This tool allows patients to browse a classification system that includes over 100 symptoms and select the symptoms they experience under the appropriate category. During the design process it became apparent that this structure presents considerable challenges to patients. There is a need to: 1) provide more flexible views of symptom categories, 2) display relationships between symptoms, and 3) make use of limited screen space. The first phase of usability testing has also shown a need for better visualization tools for viewing the symptom classification.