Protons with energies E > 135 kev were observed in the tail of the magnetosphere after the flare of July 7, 1966. These protons have an isotropic pitch‐angle distribution. The maximum intensity of the protons reached ∼1.2 × 10⁴ (cm² sec ster)⁻¹ for particles with P > 15 Mv between 1000 and 1100 UT and 1400 and 1500 UT July 8, 1966. The energy spectrum of the protons expressed as an exponential in rigidity indicates a monotonic softening: the characteristic rigidity, P_o, changing from about 50 to 10 Mv. An hour‐long excursion of the satellite into the magnetosheath during the peak of the proton flux showed that the proton intensity is lower in the magnetosheath than in the magnetosphere by a factor of 2. The observed pitch‐angle distribution is flat in both regions.