Abstract:Some enzyme activities of carbon metabolism in leaves of two rice hybrid progenies and their parents were compared. The rice hybrids used were Qingyou 159 [from Qing A and R159 ] and Guangyou No.4 [from Guang A (Y ) and Qingliuai ]. It was found that the activity of RuBPCase, and the RuBPCase/RuBPOase ratio in both hybrids were higher than those ifl their own parents. The activities,of glycolate oxidase and RuBPOase, the photorespiration(Pr) and Pr/Pn ratio in both rice hybrids were Iower than those in their respective parents. Statistical analysis showed that.the photosynthetic rates (Pn) were in postive correlation with RuBPCase activity (r=0.768), and in negative correlation with the aCtivity of glycolate oxidase (r=-0.834). Both correlation coeffcients were significantly different at p=0.05 levels.