Abstract: Open-top chambers (OTC’s) were conducted to determine interactive effects of atmospheric CO2 and O3 air pollution on photosynthetic responses in wheat. The plants were grown full-season in these chambers supplied with charcoal-filtered air (CF) as control, CF + 155μL CO2 L–1 as high CO2, non-filtered air (NF) + 40nL O3 L–1 as high O3 and NF + 155μL CO2 L–1 + 40nL O3 L–1 as combined high CO2 and high O3. Photosynthetic rates (Pn) were measured three times during vegetative and reproductive stages with portable gas exchange system (LI-COR 6200). In general, Pn rates were stimulated by high CO2 and reduced by high O3 but in some cases, combined high CO2 and high O3 increased the Pn rates. The data showed continuous increases in Pn rates during pre-flowering and early seed formation and drops during late seed formation stage. This study supports that the concentration of CO2 at 5 ± 500μL L–1 treatment had a protective role against adverse impacts of O3 exposure at concentration 5 ± 60nL L–1 treatments.