Abstract: α, β-Dibromophenyl propionyl chloride with substituents on the phenyl ring reacts with sec-butylamine or isopropylamine at a ratio of 1:4.5 (mole). The reaction would be favourable to the formation of a mixture containing almost equal amount of cis and trans geometrical isomers. By this method and preparative TLC, ten pairs of geometric isomers such as m-chloro-α-bromo-N-sec-butylcinnamamides were obtained. The anticonvulsant activities of cis-p-bromo and p-chloro-α-bromocinnamoyl sec-butylamine were found to be more potent than those of the others. Pharmacological evaluation showed that the configuration of these isomers displayed important effect on the anticonvulsant activity. Besides, the substituents on the phenyl ring and the nitrogen of amide had some influence too.