Mg alloys are characterised by several promising properties, including a good biocompatibility. In this work, a commercial AZ91 powder was used to produce cylindrical specimens by spark plasma sintering (SPS), and the specimens were further consolidated by hot extrusion. The SPS materials were found to be quite brittle because of the low bonding between the original powders. After hot extrusion, however, they displayed a ductile behaviour as revealed by room temperature tensile tests and hot compression tests. The metallographic investigation showed that extrusion induced a dynamic recrystallisation with grain refinement, but also an increase in the β phase content, which reduced the corrosion resistance of the materials.