High temperature compressive properties in AZ31 magnesium alloy were examined over a wide strain rate range from 10(-3) to 10(3) s(-1). It was suggested that the dominant deformation mechanism in the low strain rate range below 10(-1) s(-1) was dislocation creep controlled by pipe diffusion at low temperatures, and by lattice diffusion at high temperatures. On the other hand, analysis of the flow behavior and microstructural observations indicated that the deformation at high strain rates of similar to 10(3) s(-1) proceeds by conventional plastic flow of dislocation glide and twinning even at elevated temperatures. (C) 2005 Springer Science + Business Media, Inc.