Density values of the upper atmosphere derived from the rate of development of the orbits of earth satellites suffer from errors introduced by uncertainties in the determination of the mean drag cross section. As a result it is difficult or impossible to detect minor variations in the density such as, for example, its latitude dependence. An analysis is developed which circumvents this difficulty by considering the behavior of a dynamically simple parameter—the square of the product of the semimajor axis and the eccentricity. Examples from published orbital data are discussed, showing clearly the presence of a latitude dependence, and estimates of the ratio of polar to equatorial density are deduce