Ion temperatures measured by the retarding potential analyzer carried aboard the Pioneer Venus Orbiter were sorted according to the ionospheric magnetic field conditions. It was found that the dayside ion temperatures measured during the first couple of years of operations, corresponding to solar maximum conditions and while the periapsis was held at low altitudes (~150 km), were basically independent of the magnetic conditions. This contrasts with earlier studies, which showed that electron temperatures are significantly elevated when the ionosphere is magnetized. Theoretical studies by Cravens et al. [1980> predicted that electron temperatures will depend on fluctuating magnetic fields, but not the ion temperatures. This is consistent with these findings.¿ 1997 American Geophysical Union