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It is predicted that the current atmospheric CO2concentration will be doubled and global mean temperature will increase by 1.5–6°C by the end of this century. Although a number of studies have addressed the separate effects of CO2and temperature on plant-insect interactions, few have concerned with their combined impacts. In the current study, a factorial experiment was carried out to examine the effect of a doubling CO2concentration and a 3°C temperature increase on a complete generation of the brown planthopper (Nilaparvata lugens) on rice (Oryza sativa). Both elevated CO2and temperature increased rice stem height and biomass of stem parts. Leaf chlorophyll content increased under elevated CO2, but only in ambient temperature treatment. Water content of stem parts was reduced under elevated temperature, but only when coupled with elevated CO2. Elevated CO2alone increased biomass of root and elevated temperature alone enhanced leaf area and reduced ratio of root to stem parts. Brown planthopper (BPH) nymphal development was accelerated, and weight of and honeydew excretion by the F1adults was reduced under elevated temperature only. Longevity of brachypterous females was affected by a significant interaction between CO2and temperature. At elevated temperature, CO2had no effect on female longevity, but at ambient temperature, the females lived shorter under elevated CO2. Female fecundity was higher at elevated than at ambient temperature and higher at elevated CO2than at ambient CO2. These results indicate that the combined effects of elevated temperature and CO2may enhance the brown planthopper population size.