: Recent advances in Information and Communication Technologies (ICT) and more specifically in wireless networks and mobile computing have driven new directions in the development of eHealth sector. New emerging concepts like mobile health (m-Health) and Personal Health Systems (PHS) are expected to revolutionize the way healthcare services are delivered. In the paper a description on the specifics of the PHS's building blocks is presented. An example multi-tiered architectural model for realization of PHS is included and a description of characteristics and functions of the tiers is suggested. Key words: Personal Health Systems (PHS), Body Sensor Networks (BSN), Medical Web Portals, Web-based PHS.