Magnesium alloys are promising light structural materials. The present paper focuses on fine-grained magnesium-based materials. Grain refinement is attained by hot working without additional treatments. Also, a very small grain size of less than 1 mu m is obtained by equal channel angular extrusion. A good combination of high strength and high ductility at room temperature is attained by grain refinement. Furthermore, fine-grained magnesium-based materials exhibit superplastic behavior at high stain rates (greater than or equal to 10(-1) s(-1)) or low temperatures (less than or equal to 473 K). These point out the importance of grain refinement to process magnesium-based materials with excellent mechanical properties.