of the diverse range of their biological properties. A brief survey on the biological importance and the literature synthetic methods as well as the chemistry of quinazolinone derivatives is given. This investigation describes the synthesis of 2-methyl-4-oxo-3-quinazolineacetic acid hydrazide (III) starting from anthranilic acid. The reaction of compound III with p-toluene sulfonyl chloride gave the sulfonamide derivative IV. The acid hydrazide III underwent cyclization when reacted with ethyl chloroformate in n-butanol under reflux to give 5-oxo-1,3,4-oxadiazole V which upon hydrazionlysis afford the compound VI. Also, It was reacted with cyclic anhydride namely succinic and phythalic anhydride to give succinamido and phythalimido derivatives VII a, b respectively. In addition, the compound III was reacted with carbon disulphide in ethanolic potassium hydroxide to give the potassium dithiocarbazate salt VIII which was cyclized into 1,3-thiazoles IX a-c, 1,3,4-oxadiazole X, 1,3,4-thiadiazole XII and 1,2,4-triazole XIV derivatives via the reaction with phenacyl bromide derivatives, reflux in ethanol, stirring with conc. H2SO4 and reaction with hydrazine hydrate, respectively, furthermore, the oxadiazole X and thiadiazole XII were alkylated via the reaction with different alkyl halides in DMF containing potassium carbonate to give the thioether derivatives XI a-f and XIII a-d, respectively. 4-Amino, 1,2,4-triazole-5-thione derivative XIV, was reacted with aromatic aldehydes, phenyl isothiocynate and acetic anhydride to give azomethine derivatives XV a, b, thiourea XVI, N-acetyl derivative XVII. The triazole XIV was cyclized into the triazolothiazole derivatives XVIII, XIX and the triazolothiadiazine derivative XX by the reaction with acetic acid in phosphorous oxychloride, carbon disulphide and p-chlorophenacyl bromide, respectively. Reaction of the acid hydrazide III with 5,5-dimethyl-1,3-cyclohexanedione (dimedone) in toluene gave the enaminone derivative XXI which was reacted with 3-p-nitrophenyl-2-cyanoacrylonitrile in ethanol under reflux to give the hexahydroquinoline derivative XXII. However, the acridinedione derivative XXIII was synthesized from the reaction of the enaminone XXI and 3-p-nitrophenyl-2-cyano acrylonitrile in acetic acid under reflux. The in vivo evaluation of anti-inflammrtory activity of the synthesized compounds (IX a, b, XI c, d, XIII a, b, XIV, XIX) was accomplished using carrageenin-induced rat paw edema method in comparison with celecoxib as a standard, besides gastric ulcerogenic activity using indomethacin as a reference drug, results showed that the tested compounds exhibited significant ant-inflammatory activity with low gastric ulcerogenicity. The compounds IX b, XIII b and XI c found to be more effective than celecoxib.