in　this　paper,　we　design　and　present　a　novel　real-time　sleeping　position　monitoring　system.　The　sensing　modules　composed　of　3-axis　accelerometers　are　placed　on　object＇s　forehead　and　chest　to　monitor　the　object＇s　position　during　sleeping　by　calculating　the　angles　between　gravity　vector　and　its　three　axes.　System　is　driven　by　an　inexpensive　and　low　power　microcontroller.　In　this　system,　we　implement　a　proposed　novel　CORDIC-based　algorithm　on　the　embedded　microcontroller　so　that　the　system　is　capable　of　transferring　the　raw　data　of　the　accelerometer　from　motion　domain　to　angular　domain　in-line,　and　the　system　can　provide　the　inclination　or　tilt　angle　information　by　itself　in　real-time.　The　sleeping　position　information　is　integrated　into　polysomnography　(PSG)　to　cooperate　the　study　of　obstructive　sleep　apnea　(OSA)　syndrome.　©　2012　IEEE.