A wind turbine blade with a flow guiding device attached to a profiled contour on a pressure side of the blade is described. The flow guiding device extends along at least a longitudinal part of a transition region of the blade and is arranged so as to generate a separation of airflow along at least a central longitudinal portion of the flow guiding device from the pressure side of the blade at a point between the flow guiding device and a trailing edge of the blade, when the blade is impacted by an incident airflow. The inflow surface, in at least the central longitudinal portion, is formed so that, for each transverse cross-section, a end point tangent to the inflow surface at the end point crosses the profiled contour at a crossing point, where the profiled contour has a profile tangent to the profiled contour, and wherein an angle between the profile tangent and the end point tangent is at least 45 degrees.