Observations of ionospheric composition made by DE 2 in the mid-latitude ionosphere, show that during the solar maximum period of 1981, at altitudes near 900 km during the nighttime, the dominant light ion species is He+. Conditions may arise in which He+ is the dominant ion species, exceeding the O+ concentrations by a factor of 2. This observation is contrasted by those at the same altitude near the dip equator. Here a deep minimum in the He+ concentration accompanies observed maxima in the O+ and H+ concentrations and O+ is always the major ion species. Calculations are used to illustrate that the distribution of neutral species at solar maximum, together with the appropriate ionization rates can easily account for the dominance of He+ at mid-latitudes. The relative abundance of the ionospheric species is a sensitive function of local time and the associated evolution of the topside O+ concentration profile. Factors such as E¿B drift may easily effect the precise nature of the observation. At the dip equator the existence of an E¿B drift motion of the plasma is required to explain the He+ minimum. Here the E¿B drift is such that plasma observed near 900 km during the night, has resided at altitudes below 600 km during the day. Thus the He+ concentration is only that which is produced in one day against the chemical loss process. This is contrasted with the situation at mid-latitudes where the large flux tube volume provides a reservoir in which the He+ can accumulated each day. ¿ American Geophysical Union 1990