Eighteen events of large amplitude (0.4--6 &ggr;) 1- to 30-Hz waves which may be propagating in the ion cyclotron mode have been observed on Explorer 45. Comparison with simultaneously measured proton distributions has allowed the events to be divided into two categories. The first category consists of waves accompanied by enhanced ion fluxes apparently injected into the plasmasphere with anisotropic pitch angle distributions. This simultaneity suggests that these waves may be generated by the observed ring current ions. Waves in the second category were found near or outside the plasmapause and were not correlated with any identifiable changes in the observed proton distribution. The generation mechanism for these waves remains unknown.