In arid regions, emissions of nitrogen (N) gases are important to long-term soil fertility and regional atmospheric chemistry, making alterations in N gas emissions an important aspect of ecosystem response to climate change. Studies at the Nevada Desert FACE Facility suggest that rising atmospheric CO2 concentrations impact ecosystems N dynamics in the Mojave Desert; our objective was to identify whether those responses translate into changes in trace N gas emissions. We measured soil fluxes of reactive N gases (NO, NOy, NH3) and N2O in plots receiving long-term fumigation with ambient and elevated (550 ppm) CO2. Reactive N gas emissions were significantly lower under elevated CO2 during high soil moisture conditions in the spring and fall. The strongest responses occurred in the islands of fertility created by the dominant shrub Larrea tridentata, where fluxes were 3-5 ng N m-2 s-1 lower in elevated CO2 plots. Changes in total N gas emissions were driven by reduced NO and NH3 emissions, with smaller changes in NOy efflux and little to no production of N2O. Lower N gas emissions under elevated CO2 reflect changes in plant and microbial demand for N, suggesting increased uptake or immobilization coupled with decreased rates of N mineralization and nitrification. This response of N gas efflux to elevated CO2 in the growing season suggests that in deserts, elevated CO2 promotes ecosystem retention of N during periods of peak biological demand. Concomitantly, exposure to elevated CO2 alters inputs of new reactive gases into the atmosphere, potentially impacting local atmospheric processes.