The paper reports Pioneer 10 and 11 observations of the variation with heliocentric distance of the intensity of cosmic-ray protons, alpha particles, and high-Z nuclei with kinetic energies of at least 480 MeV/nucleon as well as cosmic-ray electrons with energies exceeding 6 MeV. The observations were with three-channel Cerenkov counters at distances between 1.02 and 4.66 AU while the spacecraft traveled from earth to Jupiter. During the 4.5-month observation period, all the counting rates rose steadily, except when they were modified by solar events, Forbush decreases, and Jovian electron events. Two methods are employed to determine the cosmic-ray integral intensity gradient for the observation period from simultaneous data obtained by the two spacecraft; effects of solar particles, Forbush decreases, and Jovian electrons are eliminated in various ways. A radial gradient of 0.15 + or - 2.3% per AU is determined, which is considered to be consistent with zero. Theoretical gradients are computed, and the observed values are found to be an order of magnitude below the expected values. Several reasons for the discrepancy are suggested.