Volatile compositions in transgenic Bt cotton variety 'GK-97' and its parental variety 'Simian No. 3' were analysed, and antennal response of cotton bollworm (Heliocoverpa armigera) to the volatiles were investigated. Volatile components in Bt cotton and regular cotton were almost same, except for absence of a sesquiterpene and a minor unknown compound in regular cotton. The results of gas chromatography-electroantennographic detection (GC-EAD) experiments showed that cotton bollworm antennae responded to seven compounds and two minor unknown compounds in Bt volatiles, among which concentrations of a -pinene and b-pinene in Bt cotton were relatively higher than those in regular cotton, and one minor unknown compound was absent in regular cotton.