This book includes four chapters (from chapter III-VI). Chapter I and II are already published under the title ¿An overview of phenoxazine and its synthetic intermediates¿. Chapter III is concerned with the synthesis of isoxazole and pyrazole incorporated phenoxazines to generate novel fused heterocyclic analogues. In chapter IV the synthesis of newer series of pyrimidine condensed carbazole (or azacarbazole) fused phenoxazines is described. Chapter V presents the synthesis of various substituted azepines and quinoline derivatives of phenoxazine fused carbazoles (and azacarbazole). The chapter VI describes the results obtained on in vitro screening of ten representative members selected from each class to study their antibacterial and antifungal activity.