The first measurements of the production of nitric oxide (NO) by a laboratory discharge in a simulated Venus atmosphere (CO2 96% and N2 4%) are presented. The average NO yield over a range of energies was found to be 3.7¿0.7¿1015 molecules joule-1. Simultaneous measurements of carbon monoxide (CO) resulting from the lightning-induced dissociation of carbon dioxide (CO2) indicated a CO yield of about 4¿1017 molecules joule-1 (presumably with a comparable yield of atomic oxygen). These measurements suggest that at and below cloud level, a region where solar ultraviolet radiation cannot penetrate, the dissociation of CO2 by lightning may be a significant source of oxygen atoms. Depending on the assumed value for the total energy dissipated by lightning on Venus (which is not known), the production of NO by lightning may be a significant sink of atmospheric nitrogen (in the absence of recycling) over the history of Venus.