summary The Hospital Without Walls is an ongoing ambitious project in home telecare that incorporates research into physiological monitoring, low-power radio communication, database storage of physiological data and methods of viewing clinically relevant information from large quantities of stored data. The system records vital signs from patients in their homes using a body-mounted, two-way radio system and a base station located in the home, which transmits data records to a central recording facility every day or in response to predefined emergency events. The prototype system has successfully undergone preliminary clinical trials, with a particular clinical emphasis on monitoring activity using three-axis accelerometers. Our experience with the trial suggests that there are significant differences in the technical design required for a long-term, home monitoring system and one where monitoring takes place in an environment staffed by health professionals.