Method for balancing a fan by means of a controllable laser device that is arranged outside the fan and is designed to generate a laser beam, which fan comprises a fan housing and a rotor rotatably mounted in the fan housing; which rotor comprises a rotary spindle and a rotor peripheral surface (24, 26) and is made, in at least one rotor portion (92; 430), of a material that can be machined by the laser beam, which rotor portion (92; 430) is located on the rotor peripheral surface (24, 26); which fan housing is designed in at least one housing portion such that it allows the rotor portion to be machined by means of the laser device by a laser beam emanating from said device and extending through the housing portion to the rotor portion; which method comprises the following steps: A) the rotor of the fan is rotated; B) the imbalance produced by the rotor is measured to determine at least one machining site (432a to 432k) in the predetermined rotor portion (92; 98; 430), which machining site (432a to 432k) is suitable for reducing the measured imbalance; C) the laser device is actuated to generate a laser beam in such a way that said beam is directed at an impingement site on the predetermined rotor portion (92; 430) of the rotating rotor, which rotor portion (92; 430) is located on the rotor peripheral surface; D) the laser device is actuated such that, when the impingement site (13', 13", 13''') is located within the predetermined rotor portion (92; 430) located on the rotor peripheral surface, material is removed from the rotating rotor by removing the material that can be machined by the laser beam from the at least one determined machining site (432a to 432k); E) after the imbalance has been reduced, the impingement site (13', 13", 13''') of the laser beam is moved within the predetermined rotor portion (92; 430) located on the rotor peripheral surface to a different site (13") from the preceding impingement site; F) the laser device is again controlled according to step D) in such a way that, when the impingement site (13', 13", 13"') is located within the predetermined rotor portion (92; 430) located on the rotor peripheral surface, material is removed from the rotating rotor by removing the material that can be machined by the laser beam from the at least one determined machining site (92; 432); G) steps E) and F) are repeated until such an amount of material is removed from the at least one determined machining site (432a to 432k) of the predetermined rotor portion (92; 430) as to reduce the imbalance determined in step B). A) the rotor of the fan is rotated; B) the imbalance produced by the rotor is measured to determine at least one machining site (432a to 432k) in the predetermined rotor portion (92; 98; 430), which machining site (432a to 432k) is suitable for reducing the measured imbalance; C) the laser device is actuated to generate a laser beam in such a way that said beam is directed at an impingement site on the predetermined rotor portion (92; 430) of the rotating rotor, which rotor portion (92; 430) is located on the rotor peripheral surface; D) the laser device is actuated such that, when the impingement site (13', 13", 13''') is located within the predetermined rotor portion (92; 430) located on the rotor peripheral surface, material is removed from the rotating rotor by removing the material that can be machined by the laser beam from the at least one determined machining site (432a to 432k); E) after the imbalance has been reduced, the impingement site (13', 13", 13''') of the laser beam is moved within the predetermined rotor portion (92; 430) located on the rotor peripheral surface to a different site (13") from the preceding impingement site; F) the laser device is again controlled according to step D) in such a way that, when the impingement site (13', 13", 13"') is located within the predetermined rotor portion (92; 430) located on the rotor peripheral surface, material is removed from the rotating rotor by removing the material that can be machined by the laser beam from the at least one determined machining site (92; 432); G) steps E) and F) are repeated until such an amount of material is removed from the at least one determined machining site (432a to 432k) of the predetermined rotor portion (92; 430) as to reduce the imbalance determined in step B).