Abstract: Objective To study the body position-induced changes of blood pressure（BP） in hypertensive patients and possible influencing factors.Methods With a standard mercury sphygmomanometer（CBP） and ambulatory blood pressure monitoring（ABP）,standing,sitting and supine BP measurements were carried out in turns in 334 hospitalized hypertensive patients when they kept the above body positions for 2 hours respectively.During the testing,BP was taken by ABP per 15 min,while CBP measured at the end of each posture period.Clinical characteristics and medication,such as the subjects’ body weight,height,bilateralis pulses and blood glucose levels,were also observed.Results Both systolic and diastolic blood pressures（SBP and DBP respectively） were significantly different among standing,sitting and supine positions except ABP-SBP.CBP-SBP in supine position was higher compared to that in standing and sitting position by（6.0±1.0）/（2.6±0.9） mm Hg respectively,P＜0.05,but CBP-DBP in supine position was lower than in standing and sitting position by（1.8±0.8）/（2.4±0.7）mm Hg respectively,P＜0.05;ABP-DBP were significantly lower in supine position than in standing and sitting position by（7.3±0.8）/（7.2±0.7）mm Hg respectively,P＜0.05.Except supine DBP,ABP-BP was significantly higher than CBP-BP in standing,sitting and supine positions by（8.6±15.0）/（4.4±11.9）mm Hg,（7.3±16.4）/（3.7±12.2）mm Hg,and（2.9±15.2）mm Hg respectively,P＜0.05.Multivariate regression analysis showed that the duration of hypertension,gender and fasting plasma glucose（FPG） were independent factors of SBP variation（P＜0.05）,while age and cholesterol were independent predictors for DBP variation（P＜0.05）.Conclusion The change of body position contributes to variations of blood pressure in hypertensive patients.Blood pressure levelsare significantly different in each position.Such factors as the course of hypertension,age,FBG and cholesterol can result in blood pressure variations among standing,sitting and supine positions.