The necessary conditions for the occurrence of 2D coupled galloping oscillations and adescription of the set of general differential equations for 2D coupled galloping vibrations are estab-lished in this paper. A procedure to predict the 2D coupled galloping oscillalions is proposed. Windloading was treated as a stochastic process including mean and fluctuating components caused by at-mospheric turbulence. The formulae and the procedure presented permit a better assessment of gallop-ing oscillations of a prismatic structure which has the same natural frequencies in the directions of thetwo orthogonal horizontal axes. The effects of turbulence on 2D coupled galloping are investigated. Itis shown that 2D coupled galloping oscillations mainly occur in the cross-wind direction. The effect ofthe turbulence integral scale on the onset wind velocity of 2D coupled galloping oscillations is negli-gible. However, the turbulence integral scale has certain influences on the rms response both in thealong-wind and the cross-wind directions when the wind velocity is equal or close to the onset wind vel-ocity for galloping. An increase in the turbulence integral scale in the range of 10--40 m considered inthis paper increases the galloping response.