The scheme of this work involves synthesis and evaluation the biological activity of some new 1,3,4-oxadiazole compounds derived from 3-nitrobenzoic acid as starting material. This work is divided into four parts: First part: This part involved synthesizing 2-mercapto-5-)3-nitrophenyl)-1,3,4-oxadiazole [3] which derived from the reaction of compounds 3-nitrobenzoic acid [0], ethyl-3-nitrobenzoate [1],3-nitro benzoic hydrazide [2], with different organic compounds. Second part: This part involved synthesizing of phthalazin,pyridazin-dione derivatives and Schiff base, from the reaction of material 2-hydrazido-5-(3-nitrophenyl)-1,3,4-oxadiazole [4] with different organic compounds. Third part: This part involved connecting p-aminoacetophenone, glycine with compound [3] 2-mercapto-5-(3-nitrophenyl)-1,3,4-oxadiazole through elimination reaction. Then synthesizing bis 1,3,4-oxadiazole compound which derived from the reaction of compounds [5-(3-nitrophenyl)-[1,3,4-oxadiazole]-2-ylamino]-acetic acid [12], 5-(3-nitrophenyl)-2-aminoethylacetate-1,3,4-oxadiazole [13], 5-(3-nitrophenyl)-2-aminoacetic acetic acid hydrazide-1,3,4-oxadiazole [14] with different organic compounds. Forth part: This part involved evaluate the biological activity of some synthesized compounds for their antimicrobial activity against two strains of pathogenic microorganism Gram positive bacteria Staphylococcus aureus and Gram negative bacteria Escherichia coli.