The nearly equatorial trajectory of the Pioneer II spacecraft through Saturn's high energy proton radiation belts and under the main A-B-C rings provided a unique opportunity to study the radial dependence of the >30 MeV proton intensities in the belts in terms of models for secondary nucleon production by cosmic ray interactions in the rings, in situ proton injection in the radiation belts by neutron beta decay, magnetospheric diffusion, and absorption by planetary rings and satellites. Maximum trapped proton intensities measured by Pioneer II in the radiation belts are compared with calculated intensities and found consistent with trapping times ≈40 years and a radial diffusion coefficient DLI≈10-15L9RS2/s. Differential energy spectra J(E)∝E-2 estimated from integral measurements of trapped protons with E>102 MeV are consistent with the beta decay model, but an inferred turndown of the spectra toward lower energies and reported integral proton anisotropies of the form J(&agr;eq)∝sin4--6&agr;eq both indicate the need for more realistic calculations of the neutron source from the rings and the radiation belt loss processes.