Abstract: This talk is devoted to the study of gravity waves in the atmospheres of Solar System planets using various theoretical and observational approaches in the framework of comparative planetology. I will focus on the results of a number of ground based observations and ongoing experiments from current NASA space missions to Jupiter, Saturn and Mars. These observations aim to constrain the spectral characteristics of the present gravity wave modes and to understand the dominant sources of wave activity in the atmospheres of giant and terrestrial type planets.