A method for balancing a plurality of cylinders during gaseous fuel operation of an internal combustion engine having a plurality of gas admission valves (38) comprises operating the internal combustion engine with a first common ignition timing for each of a plurality of cylinders. While operating with the first common ignition timing, a cylinder (26) having an above-average knock level is determined, and an opening duration of the gas admission valve (38) associated with this cylinder is reduced. This is repeated until the knock levels for all cylinders differ from each other by less than a predetermined amount. When the knock levels for all cylinders differ by less than the predetermined amount, the first common ignition timing is advanced to a second ignition timing.