It is well known that some hydrazone derivatives of both 2-oxobenzoxazoline and 2-oxobenzothiazoline exhibit potent anticonvulsant activity. In order to investigate the effects of structural modifications on the biological properties, 14 new hydrazones of 5-chloro-2(3H)-benzox-azolinone-3-acetyl hydrazide were synthesized. The chemical structures of the synthesized compounds were established by IR, 1H-NMR spectral analyses and elementary analyses. The anticonvulsant activities of the title compounds were tested by the penthylenetetrazole induced seizure test. 5-Chloro-2(3H)-benz-oxazolinone-3-acetyl-2-(o-methoxy-benzaldehyde)-hydrazone 4d, 5-chloro-2(3H)-benzoxazolinone-3-acetyl-2-(o-methybenzaldehyde)-hydrazone 4g, 5-chloro-2(3H)-benzoxazolinone-3-acetyl-2-(p-methylbenzaldehyde)-hydrazone 4h, 5-chloro-2(3H)-benzoxazolino-ne-3-acetyl-2-(p-nitrobenzaldehyde)-hydrazone 4m, and 5-chloro-2(3H)-benzox-azolinone-3-acetyl-2-(p-dimethylaminobenzaldehyde)-hydrazone 4n were found more active than phenytoin (CAS 57-41-0) in the tests.