Results of observations made with the Zeeman Modulator Radiometer (ZMR) at a high-altitude observatory during the MAP/GLOBUS NOx campaign in September 1985 are presented. These results show unexpected short-term variabilities in the NO column above 25 km. Possible causes for these are discussed. These variations are filtered out in hourly averages, which shown NO columns that typically increase from 2¿1015 molecule cm-2 shortly after sunrise to an afternoon maximum of 3¿1015 molecule cm-2, followed by a small decrease in the late afternoon. These columns are similar from day to day over the 3-week observation period. The observed column amount of NO and its diurnal variability are consistent with the predictions of the Cambridge one-dimensional diurnal photochemical model. Observations of NO2 imply that when the likely mesospheric contribution to the NO column is considered, the measured and predicted NO/NO2 column ratios are in agreement. ¿ American Geophysical Union 1988