Abstract:The activities of respiratory enzymes in cytoplasmic male sterile (CMS) rice Zhenshan 97A and its maintainer Zhenshan 97B were studied. The results showed that the activities of malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH), glucose-6phosphate dehydrogenase (G6PDH), 6-phospho-gluconate dehydrogenase (6PGDH) and 5-Phosphoribose isomerase (RSPI) in sterile anthers were all lower than those in fertile ones.But in panicles only the activities of G6PDH, 6PGDH and RSPI in sterile line were lower than those in fertile line. The results indicated that the cytoplasmic sterility of rice was associated with the obvious decrease of tricarboxylic acid cycle(TCA) and pentose phosphate pathway (PPP) activities, and the change in PPP operation was shown to be earlier than that in TCA.