The lightest structural metal present on Earth’s surface is Magnesium (Mg). Mg is very useful for many applications like automobile, aeronautical etc. Mg has many limitations and because of which it cannot be used directly as a replacement of steel and aluminum. Different alloys of magnesium have been developed to partially or completely overcome the limitations of magnesium without sacrificing other properties. The most commonly used commercial alloys are in almost all the fields is magnesium alloy AZ91, which gives better properties than magnesium. This paper mainly aims at study the mechanical properties of magnesium based AZ91 alloy. The results were compared with the as-cast condition. Present investigated material has been obtained by using die casting technique. Mg material is subjected to T6 heat treatment which has two stage process involving combination of solution annealing at 413 °C for 13 h and subsequent aging at 200 °C for 10 h. Micro structural and mechanical properties like hardness of the specimen were studied. Useful survey shows that hot working of AZ91 alloy provides high mechanical properties unattainable by cast material subjected to heat treatment. The microstructure is observed under the optical microscope.