Pyrimidines are well known for their anticancer, antimicrobial, antioxidant and antiviral activities (1-5). Oxadiazoles are well known for their antifungal, antibacterial, anticancer and anticonvulsant activity (6-10). Indoles are also well known compounds for their antimicrobial, anticancer, antioxidant and antiviral activity (11)(12)(13)(14)(15). In the present investigation nine pyrimidinone-oxadiazolyl indolinones were prepared. The synthesized indole derivatives of oxadiazolyl-pyrimidinones were tested for their antimicrobial and antioxidant activities. Reaction of ethyl-6-methyl-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidin-5-carboxylates (1a-i) with hydrazine hydrate yielded 6-methyl-2-oxo-4-aryl-1,2,3,4-tetrahydropyrimidin-5-carbohydrazides (2a-i). These products, on reaction with cyanogen bromide, gave 5-(5-amino-1,3,4--oxadiazol-2-yl)-6-methyl-4-aryl-3,4-dihydropyrimidin-2 (1H)-ones (3a-i). The resultant aminooxadiazolylpyrimidinones were condensed with isatin to obtain various 3-{[5-(6-methyl-4-aryl-2-oxo-1,2,3,4-tetrahydropyrimidin--5-yl)-1,3,4-oxadiazol-2-yl]-imino}-1,3-dihydro-2H-indol--2-ones (4a-i). These products were characterized by IR, 1 H NMR, mass spectra and elemental analysis. Products (4a-i) revealed promising antibacterial, antifungal and antioxidant activity.