Abstract: A wind turbine comprising an axis intended for vertical mounting, blades arranged around the axis, and mounting arms. Each blade comprises a substantially symmetric aerofoil and is of substantially straight section lengthwise. The mounting arms are coupled to the axis and extend substantially perpendicular to the axis. Each mounting arm comprises a fairing of aerofoil shape. Each blade is mounted to the axis at both ends on respective mounting arms. The mounting arms of each blade are angularly spaced around the axis such that each blade is arranged rotated at an angle to the vertical in use and one arm leads the other when the turbine is rotating.