Effect of pass strain (Deltaepsilon) on grain refinement was studied in multiaxial compression (MAC) of a coarse-grained 7475 Al alloy at 763 K under a strain rate of 3x10(-4)s(-1). The value of Deltaepsilon influences significantly the kinetics of grain refinement. MAC of Deltaepsilon=0.7 results in a substantial grain refinement in high strain, finally leading to formation of a fine grain structure with a mean size of 7.5 mum and the volume fraction of about 85%. In contrast, MAC of Deltaepsilon=0.4 leads to formation of a smaller volume fraction of fine grains with the similar grain size. The grain refinement mechanisms operating under hot MAC are discussed in some details.