Abstract. This study investigates the aerodynamic loads and energy losses of a typical 600 kW wind turbine with S816 airfoil blade under two di erent icing conditions. Three sections at di erent radial positions were considered to estimate the icing e ect along the blade. Ice accretion simulations in wet and dry regimes were carried out using the NASA LEWICE 3.2 computer program. The air ow simulations were performed with CFD method and SST k ! turbulence model. The results of these simulations, including streamlines, surface pressure, skin friction, lift, and drag coe cients, were inspected for both clean and iced airfoils. In the case of wet iced airfoil, a separation bubble was created in the leading edge due to a horn-shaped ice and then further downstream, the air ow was reattached. Ice-induced separation bubbles dominate the ow eld and aerodynamic performance of the wind turbine. In order to assess the production losses, the Blade Element Momentum (BEM) theory was used to calculate the power curves for clean and iced wind turbine blades. In the case of dry regime, deterioration of the performance is about 30% and, in another case, the turbine fails to produce any power at all.