Wearable　health-monitoring　system　requires　keeping　the　balance　between　energy　consuming　and　user＇s　real-time　service　demands　with　continuous　sensing,　wireless　communication　and　processing.　In　this　paper,　we　present　a　design　framework　for　an　Energy　Efficient　Wearable　Health-monitoring　System　(EEWHMS).　EEWHMS　uses　smartphone　as　a　central　unit　to　process　data　from　wearable　sensors,　with　event-driven　energy　management　strategy　to　save　energy.　State　transitions　and　continuous　being　still　of　user　is　used　to　adjust　duty　cycle　of　the　system.　We　present　the　design,　implementation,　and　evaluation　of　EEWHMS,　which　collects　user＇s　information　with　accelerometer　and　physiological　sensors,　and　sends　it　to　an　Android　phone　by　Bluetooth.　According　to　evaluation　of　power　of　Bluetooth　chip,　CPU　load　of　smartphone　and　response　time　when　emergency　happened,　the　system　demonstrates　its　capability　to　keep　balance　between　real　time　and　long　term　sensing　in　an　energy-efficient　manner.　©　2012　Springer-Verlag.