Observations of the particle density near the equatorial plane at different distances from the earth are compared with a theoretical study of the diffusion of charged particles injected into the geomagnetic field well beyond the outer radiation belt and subsequently scattered by fluctuating electric or magnetic fields. A survey of the diffusion process is made by considering a system with spherical symmetry, where particles are injected uniformly over a spherical shell. As the distribution widens, the particles closer to the earth are impeded by the diminishing diffusion coefficient, whereas the particles further away are rapidly dispersed. An asymmetric distribution develops with a steep slope facing the earth and a more gradual decrease outward. (B.O.G.)