The blades of a large wind turbine are subjected to significant vibrations during operation. The vibrations will impact the dynamic flow field around the blade and consequently alter the aerodynamic forces. In order to better understand the influence of blade vibrations on the aerodynamic loads, the dynamic stall characteristics of an S809 airfoil undergoing various types of motion were investigated using Computational Fluid Dynamics (CFD) techniques. Simulation results indicated that the in-plane and out-of-plane translational motions of the airfoil affect the aerodynamic forces significantly. Furthermore, the influence of vibrations on the aerodynamic loading on the blade of a 5 MW wind turbine was investigated using the Blade Element-Momentum (BEM) theory and the Beddoes-Leishman (B-L) dynamic stall model.