Actinobacteria is a separale phylum of bacterial domain with 52 families and more than 230 genera,and they are Gram-positive organisms with high G+C composition.They are well known as a rich source of antibiotics and bioactive molecules and they are thus considered to be a rich biolechnological resource.We all know that Actinobacteria are widely distributed in natural and man made environments and play an important role in the degradation of organic matter.They can be found in a variety of habitats and are particularly abundant in soil and aquatic bodies.The aim of this study is to discover the diversity of Actinobacteria in the Natural Limestone Quarries.which provide a unique and special environment,characterized by presence of high alkalinity,dryness and very liitle water and vegetation is taken up.