The present estimates or emissions of NO from soils to the atmosphere are based on field studies that used enclosure techniques. While this technique is direct, convenient and precise, the technique may perturb the biogenic soil processes under study. In addition, the limited sample size may produce nonrepresentative results. In order to address these concerns, NO flux measurements made using an enclosure technique are intercompared with NO flux determinations made using a gradient technique. The measurements were made during the nighttime hours from August to October, 1985, at an unfertilized, uncultivated grassland site in Colorado, United States. The NO flux measured during this period ranged between 0.08 ng N m-2 s-1 and 21 ng N m-2 s-1. The flux measurements made by the two techniques, which are based on very different approaches as described herein, agree very well. ¿American Geophysical Union 1987