Although the usefulness of telehomecare has been recognized, and all technologies required are readily available, expectations for its widespread adoption have not been realized. This paper presents the development of a portable telehomecare monitoring system (PTMS). What sets this work apart from most other systems is the focus on a highly decentralized monitoring model and the portable nature of the system. We believe that this is the approach that is needed to make such systems economically viable and acceptable to the end-users. The PTMS is a decentralized system, in which a single household is the fundamental unit for sensing, data transmission, data storage and analysis. It is not necessary to subscribe service from a health welfare center, and the infrastructure required is minimal, too. Equipped with different sensors, the PTMS can be used for long-term personal health data management in a home environment, and it can be easily implemented in a home environment at very low cost. Similar to the largescale telehomecare systems, the PTMS also provides caregivers with convenient access to the health data and real-time event-driven messages in urgent situations. Several PTMS applications are described in this paper, including environmental monitoring, monitoring of activities of daily living, a radiofrequency identification (RFID)-based entrance guard system, sleep quality monitoring, vital sign parameter monitoring, and a tele-presence robot.