Abstract: This paper statistically investigates the propagation characteristics of inertial gravity waves in the mesorphere with VHF radar observations at Andφya(69°N, 10°E) Norway from June 22 to June 29 1987. It is found from the observations that 21 wave examples are of good monochromaticity and have certain certical progressions of phase.Their periods are severel home, indicating they are medal internal gravity waves. The distribution of horizontal wave vectors is extimated by analysing the hodographs of wave-asspcoated horizontal fluid velocity, most (76%) of them propagate westward, it seems to be related to the intense westward background wind at mesopause, The estimated horizontal wave vectors are the typical values observed in mesosphere. There are 15 (6) examples with downward (upward) phase progressions among the 21 examples. Their vertical wave lengths range from 5 to 9 km, wave-associated velocities are from 10 to 50m/s,indicating there exists not only upward but also intense downward wave energy flux in the polar mesosphere.