This heterocyclic nucleus play vital role in biological and Medicinal field. Chapter-I describes a brief summary of the pharmacological activities of Triazole ,Oxadiazole and Thiadiazole system and highlights some examples of recent drug containing this moieties.Chapter-II describes Different synthetic methods.Further Synthesis of different 6-Methyl-4-aryl-5-(5-aryl-1,3,4-oxadiazole-2-yl)-1,2,3,4-tetrahydro pyrimidine-2- (1H)-one / thione in Chapter-III. Triazole, oxadiazole and thiadiazole a five membered heterocyclic nucleus has attracted a wide attention of the Chemist in search for the new therapeutic molecules? While Chapter-IV includes A series of... So we have developed a A series of different Triazole and Oxadiazole derivatives by adopting Green approach. This diversity in the biological response profile has attracted the attention of many researchers to explore these Skeletons to its multiple potential against several activities!