Measurements of O3, NO, NO2, peroxyacetyl nitrate (PAN), HNO3, and NOy were made during a 6-week period in the summer of 1991 in Giles County, Tennessee. These data were analyzed to determine the factors controlling the relationship between O2 and NOy at this rural site. A strong association was observed between the O3 and NOx oxidation product (NOz=NOy-NOx) levels. The higher O3 levels were associated with air masses impacted by higher NOx emissions that had been photochemically processed. An analysis of the data indicates that the ultimate O3 production is about 10 molecules of O3 produced for each molecule of NOx emitted. The analysis results also suggest that O3 net production continues until about 70% of the NOx has been converted into NOz. The PAN/HNO3 ratios observed suggest that the air masses in Giles County are composed of higher volatile organic carbon/NOx ratios than the air masses observed at other rural sites in eastern North America. A comparison of the data analysis results to model simulations and smog chamber experiments suggests that most of the time, Giles County is in an NOx-limited regime for O3 production. ¿ American Geophysical Union 1994