Triazole, oxadiazole and thiadiazole a five membered heterocyclic nucleus has attracted a wide attention of the Chemist in search for the new therapeutic molecules. This heterocyclic nucleus play vital role in biological and Medicinal field. 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. So we have developed a A series of different Triazole and Oxadiazole derivatives by adopting Green approach. 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. While Chapter-IV includes A series of 6-methyl-4-aryl-5-(5-phenyl-4H-1,2,4-triazole-3-yl)-3,4, dihydro pyrimidin- 2(1H)- one/thione. The structure elucidation of all the synthesized compounds have been accomplished by elemental analysis, IR, NMR and Mass spectroscopic method.