A method of mounting wind turbine rotor blades to a rotor hub with blade mounting sections while the rotor hub is already mounted to a nacelle located at the top of a wind turbine tower, in which - the rotor hub is kept in a same fixed rotational position for all rotor blades and the rotor blades are tilted by individual tilt angles for mounting them to the mounting sections of the rotor hub, the method comprising the steps of: a) lifting the first rotor blade from the ground; b) tilting the first rotor blade by approximately +60° or -60° with respect to the horizontal; c) fixing the first rotor blade to the wind turbine hub with the blade being tilted by approximately +60° or -60° with respect to the horizontal; d) lifting the second rotor blade from the ground; e) tilting the second rotor blade by approximately -60° with respect to the horizontal if the fist rotor blade was tilted by approximately +60° with respect to the horizontal, or tilting the second rotor blade by approximately +60° with respect to the horizontal if the first rotor blade was tilted by approximately -60° with respect to the horizontal; f) fixing the second rotor blade to the wind turbine hub with the blade being tilted by approximately -60° or +60° with respect to the horizontal; g) lifting the third rotor blade from the ground; h) fixing the third rotor blade to the wind turbine hub with the rotor blade being substantially aligned with the horizontal, wherein the nacelle is rotated about a yaw angle of 180° before the third rotor blade is mounted to the rotor hub characterized in that each rotor blade is pitched after lifting it from the ground to a certain pitch angle (θ 1, θ 2), wherein the first and second rotor blades are pitched to a first pitch angle (θ 1) of 20° with respect to the vertical and the third blade is pitched to a second pitch angle (θ 2) of 110° with respect to the vertical. - the rotor hub is kept in a same fixed rotational position for all rotor blades and the rotor blades are tilted by individual tilt angles for mounting them to the mounting sections of the rotor hub, the method comprising the steps of: a) lifting the first rotor blade from the ground; b) tilting the first rotor blade by approximately +60° or -60° with respect to the horizontal; c) fixing the first rotor blade to the wind turbine hub with the blade being tilted by approximately +60° or -60° with respect to the horizontal; d) lifting the second rotor blade from the ground; e) tilting the second rotor blade by approximately -60° with respect to the horizontal if the fist rotor blade was tilted by approximately +60° with respect to the horizontal, or tilting the second rotor blade by approximately +60° with respect to the horizontal if the first rotor blade was tilted by approximately -60° with respect to the horizontal; f) fixing the second rotor blade to the wind turbine hub with the blade being tilted by approximately -60° or +60° with respect to the horizontal; g) lifting the third rotor blade from the ground; h) fixing the third rotor blade to the wind turbine hub with the rotor blade being substantially aligned with the horizontal, wherein the nacelle is rotated about a yaw angle of 180° before the third rotor blade is mounted to the rotor hub characterized in that each rotor blade is pitched after lifting it from the ground to a certain pitch angle (θ 1, θ 2), wherein the first and second rotor blades are pitched to a first pitch angle (θ 1) of 20° with respect to the vertical and the third blade is pitched to a second pitch angle (θ 2) of 110° with respect to the vertical. a) lifting the first rotor blade from the ground; b) tilting the first rotor blade by approximately +60° or -60° with respect to the horizontal; c) fixing the first rotor blade to the wind turbine hub with the blade being tilted by approximately +60° or -60° with respect to the horizontal; d) lifting the second rotor blade from the ground; e) tilting the second rotor blade by approximately -60° with respect to the horizontal if the fist rotor blade was tilted by approximately +60° with respect to the horizontal, or tilting the second rotor blade by approximately +60° with respect to the horizontal if the first rotor blade was tilted by approximately -60° with respect to the horizontal; f) fixing the second rotor blade to the wind turbine hub with the blade being tilted by approximately -60° or +60° with respect to the horizontal; g) lifting the third rotor blade from the ground; h) fixing the third rotor blade to the wind turbine hub with the rotor blade being substantially aligned with the horizontal,