Abstract:By using thin-layer-isoelectrofocusing technique, the authors have been studied peroxidase isozymes activities of the true leaves (at the flower bud stage) and the anthers in the interspecific advanced lines (ALs) from Gossypiurn hirsuturn × G. arboreum, which have been steadily inherited from twenty generations. It was found that: 1. The peroxidase isozymes were similar in different varieties of plants from the same species, but some what different among species originated from the same genome group, and showed remarkably interspecific isozymes difference among species originated from different genome group. 2. The zymograms of the ALs were similar to those of the female parent G. hirsuturn "Keiyi 2”, and obviously different from those of the male parent G. arboreum "Wanzi”.