Benzothiazole is among the usually occurring heterocyclic nuclei in many marine as well as natural plant products. Benzothiazole is a privileged bicyclic ring system with multiple applications. It is known to exhibit a wide range of biological properties including antiviral, antimicrobial, anti-allergic, anti-inflammatory etc. Large number of therapeutic agents are synthesized with the help of benzothiazole nucleus. Due to these number of activities associated with this core structure, in this book we have given summary of some of the pyrido benzothiazole derivatives and their biological activities.