This paper describes initial experience with the Web-based Patient Clinical Information System (PatCIS). The system was designed to serve as a framework for the integration of applications that help patients access their electronic medical record, add data to their record, review on-line health information, and apply their own clinical data (automatically) to guideline programs that offer health advice. The architecture supports security functions and records user activities, relieving application developers from concerns about safe information practices and the evaluation process. PatCIS is being used to study the social and cognitive impact of allowing patients to have access to their health records via the Web. To date, PatCIS has grown to include 15 clinical functions and 4 dynamic links to literature (called infobuttons). Eleven patients have been enrolled since April, 1999; five have been active users. Experience shows that the PatCIS architecture supports application integration while providing adequate security and evaluation functions. Initial caution with the patient enrollment process has limited recruitment and, consequently, usage. However, experience thus far suggests that PatCIS has good usability and utility. No adverse events, including undesirable impact on doctor-patient interactions, have been reported. There do not appear to be any technical impediments to scaling up the enrollment to continue to observe patient usage.