The LIMS is a six channel limb scanning IR radiometer flying on the NIMBUS 7 spacecraft. It measured radiances from October 24, 1978, to May 28, 1979, from which vertical profiles of temperature, ozone, water vapor, nitrogen dioxide, and nitric acid were determined. Nitric acid (HNO3) plays an important role in stratospheric chemistry, both as reseroir and as sink for the nitrogen compounds and because of its relationship to the hydroxyl radical. This paper describes the validation of the HNO3 results, beginning with an outline of the measurements and data reduction leading to the retrievals. The error sources due to instrumental effects and data reduction are described, and their effects on the results are calculated. The predicted random errors are shown to be somewhat larger than the observed values of ~0.10 ppbv. The LIMS results are within 20% of a set of 15 correlative balloon-borne measurements, obtained with several techniques over a range of season, latitude, and pressure between 100 m 20 mbar, the region of largest HNO3 mixing ratio. This is aout the accuracy of the correlative measurements. The percent differences are larger at altitudes above 10 mbar. LIMS results agree with earlier measurements at all but the highest levels. Total overburdens above 200 mbar calculated from LIMS agree with those measured spectroscopically from aircraft. LIMS and other HNO3 measurements show similar agreement with model predictions. The consistency suggests that the major lIMS error sources are reasonably well undestood. The NHO3/NO2 ratio also leads to reasonable OH concentrations. The global distribution of HNO3 in November shows strong latitudinal variation at the altitude of the maximum, with a large build up over the northern hemisphere pole at ~40 mbar, but lower values over the southern pole. This reverses by early northern spring. Some characteristics and limits on the data are noted, but the LIMS HNO3 determinations are usually of comparable accuracy to other determinations. These results provide valuable addition to our knowledge of the distributions of trace gases in the stratosphere. By themselves, but especially in conjunction with the LIMS measurments of temperature, ozone, water vapor, and nitrogen dioxide, the form the basis for a wide range of atmospheric studies.