This study was performed to investigate if elevated CO2 affects the residue pattern of 14C in the soil environment after 14C-carbaryl treatment. 14C-carbaryl was applied on the rice plant-grown greenhouse soil exposed to atmospheric and elevated CO2 conditions. 14C-radioactivity was measured in the rhizospheric soil and rice straw samples six months after 14C-carbaryl application. Significantly high radioactivity was observed in the soil exposed to atmospheric CO2 as compared to that in the soil exposed to elevated CO2. Background level of radioactivity was observed in rice plant samples. These observations suggest the possibility that elevated CO2 may affect residual radioactivity of 14C-carbaryl in the soil rather than that in the plant.