The fluxes of NO and NO2 have been measured at a grassland site in Colorado, United States. The measurements were made using an enclosure technique during the period between Aug. 16, 1985, and Nov. 15, 1985. The fluxes ranged between 0.028 and 65 ng N m2 s-1 with an average value for all measurements of 3.0 ng N m-2 s-1. The NO flux was found to increase rapidly with increasing temperature. Large variations of NO flux with soil moisture were also observed. Under dry soil conditions, NO2 was present in the effluent from the sampling enclosure but was not present when the soil and/or vegetation covering the soil was moist. Overall, the NO2 totalled approximately 10% of the NO emissions. The results are compared with NO soil emission measurements carried out elsewhere. ¿American Geophysical Union 1987