Abstract: AIM To observe the effect of inflatable pressure suits on orthostatic tolerance and cardiovascular function in humans during lower body negative pressure (LBNP). METHODS Ten healthy subjects were randomly exposed to LBNP two times with or without pressure suits. LBNP tolerance, blood pressure, heart rate and cardiac pumping function were detected during LBNP. RESULTS The duration of LBNP in subjects with pressure suits increased significantly compared with the duration without pressure suits ［(23.3±0.9) min vs.(12.5±1.2) min］. During LBNP, total peripheral resistance and systolic blood pressure increased significantly, whereas the heart rate decreased significantly in subjects with pressure suits compared with that in subjects without pressure suits. There were no significant changes in stroke volume, cardiac output and heart rate variability. CONCLUSION Inflatable pressure suits increase human orthostatic tolerance through the improvement of blood return by increasing peripheral resistance during orthostatic stress.