Evidence for the modulation of the gravity wave activity by the equatorial waves in the tropical middle atmosphere is presented using the Rayleigh lidar observations of the temperature over Gadanki (13.5¿N, 79.2¿E) and the rocketborne measurements of winds over Shriharikota Range (13.7¿N, 80.2¿E) during the period of 29 February to 31 March, 2000. The potential energy per unit mass associated with the gravity wave activity in the upper stratosphere and mesosphere is found to undergo periodic fluctuations, which is well correlated with the zonal and meridional wind oscillations in the stratosphere produced by the equatorial waves. The most dominant modulation of the gravity wave activity due to equatorial waves is found to occur at periods around 4-days and 12-days. Minimum gravity wave activity in the mesosphere is observed during the southward phase of meridional wind and the westward phase of zonal wind oscillations in the lower stratosphere.