This paper describes the temporal characteristics of the X ray fluxes measured by a balloon-borne scintillation detector on April 14, 1981, due to electron precipitation at the South Atlantic Magnetic Anomaly and in association with a strong geomagnetic storm. The data clearly indicate the dynamical nature of the precipitation process and also give some clues on physical mechanisms that could be responsible for it. As a result, it is suggested that the modulation of the electron precipitation during this storm would have been caused by processes involving wave-particle or wave-modulated wave-particle interactions. ¿ American Geophyscial Union 1989