A Schiff base has been prepared by the reaction of 4-acetyl-5-methyl-2-(4-methylphenyl)-2,4-dihydro-3H-pyrazole-3-one with different substituted amines. Treatment of this Schiff base with chlorobactyl chloride affords the corresponding azetidinone in good yield. All the new compounds have been characterized by IR, H-1 NMR, GC -MS and elemental analysis. The antibacterial activity of these compounds has been determined with the reference of standard drug.