An investigation of the equatorial scintillation of satellite signals at 257.55 and 1541.5 MHz for about 10° and 50° elevation angles is reported. Diurnal and seasonal variations are shown for the two frequencies and the two elevation angles. A periodicity in the occurrence of the scintillation was observed and is attributed to the gravitational field of the moon. It is proposed that the moon's gravity may affect the occurrence and intensity of equatorial scintillation by modulating the velocity of the zonal winds at ionospheric heights. An additional possible contribution to the periodic variation in the scintillation is a periodic variation which occurred in the geomagnetic activity during the first half of the year.