The objective of this study was to estimate the mean relative growth rate (MRGR) of maize aphid, Rhopalosiphum maidis Fitch (Aphididae: Hemiptera), reared on maize for three successive generations under elevated CO2 (eCO2) (550 ppm ± 25 ppm) and ambient CO2 (aCO2) (380 ppm ± 25 ppm) concentrations at six temperatures of 20, 25, 27, 30, 33 and 35 ±1oC in open-top chambers and CO2 growth chambers with CO2 and temperature regulation. Experiment was conducted by adopting agar-leaf method. The impact of eCO2 with six constant temperatures on the MRGR of R. maidis was found significant in three generations. MRGR of R. maidis was significantly increased with temperature in the range of 20oC to 35oC (0.269 to 0.464 µg µg-1 day-1) under eCO2 compared to that of aCO2 conditions across the three generations. The present results obtained in this study might provide useful information to aphid control and developing management strategies.