The LIMS experiment launched on NIMBUS 7 measured vertical profiles of temperature and the concentrations of O3, H2O, NNO3, and NO2 during the period from late October 1978 until late May 1979. This paper discusses the validations of results from the NO, channel and the quality of the data. The discussion includes channel characteristics, experiment errors due to instrument and spacecraft effects, predicted and measured precision, predicted accuracy, and comparisons with correlative measurements made in a series of balloon underflights. All balloon measurements used for comparisons were made using the solar occultation technique, and since NO2 varies significantly over the diurnal cyle, a photochemical model was used to the time translate the data to the LIMS time. Because of this the comparisons were primarily qualitative. Features such as profile shape and slope of the mixing ratio altitude distribution are in good agreement. The mean difference between LIMS results and the balloon data is well within the range of the sum of the error bars for the two data sets. Comparisons are also made with past balloon measurements taken in the 40 ¿N to 50 ¿N latitude band and with photochemical model predictions of the vertical profile. The LIMS data fall within the range of previous mixing ratio measurements, and they are consistent with model estimates. The calculated on-orbit precision is ≈0.3 ppbv and the estimated accuracy from simulations is ≈2 pbv over the 3-mbar to 10-mbar range. Accuracy degrades at higher and lower pressure levels. These results provide the first day-night set of NO2 measurements from space.