Centrifugation experiments were carried out to study human tolerance to repeated acceleration +Gz of 7.5 and 8.5 G as maximal and 1.2 and 3.0 G as minimal values. The exposures were no longer than II min with the onset rate of 0.3 to 0.8 G/sec. Repeated exposures to acceleration changed their tolerance by test subjects. Further study of the effects of repeated exposures to +Gz is needed under the conditions similar to those of a real flight.