In three experimental series in which 34 male test subjects (aged 20 to 31 years) participated, acceleration tolerance (+Gz) was measured before and after exposure to 7-day head-down tilting. The measurement tests were performed using an antigravitational device in two modifications AGU-1 and AGU-2. After tilting, tolerance to sustained acceleration +Gz decreased significantly. The use of the device helped to increase acceleration tolerance, AGU-1 all the test subjects tolerated acceleration up to 4.0 G while in AGU-2 only up to 3.0 G. The use of the AGU device following exposure to antiorthostatic hypokinesia helped to maintain the high quality of operator's activities as compared to the controls.