Ion composition results obtained by Narcisi et al. (1972a) from rocket observations carried out during the November 1966 solar eclipse campaign at Cassino, south Brazil, are analyzed on the basis of the presently known detailed ion chemistry of the lower ionosphere, to deduce the height distribution of nitric oxide concentration in the region from 80 to 110 km. The results are compared with certain available experimental determinations of the NO height distributions carried out by other workers using rocket-borne radiometric measurement of NO &ggr; band emissions in the dayglow. Other available NO deductions from ion composition data are discussed in the light of the present results.