The present book described the synthesis of some new heterocyclic entities incorporating the active pharmacophores in a single molecular frame work and their biological assessment as new antimicrobial, antiamoebic and anticancer agents. The synthesis of ninety nine novel hetero-cyclic compounds of variegated nature is described in the book using multi-step procedure possessing tetrazoles, pyrazolines, oxadiazoline, pyrimidines and triazines. The detailed synthetic procedures, Biological screening and structural confirmation is briefly explained in the book that will help the readers for further developments in the similar field.