As an attempt to develop a convenient grain refinement method, wrought products of a commercial AZ31 alloy have been subjected to further cold rolling and subsequent annealing. The influence of the angle, theta, between the original working direction and the cold-rolling direction on the grain size has been also investigated. Specimens were cold-rolled by 15%, subsequently annealed at 250degreesC for 1h and then subjected to optical microscopy. The present process was found to be effective to refine the grain size. Grain refinement became more marked when theta increased. Yield strength and hardness were confirmed to increase with decreasing grain size.