An intake air filter (1) is for an internal combustion engine, especially in a motor vehicle. The filter has a filter housing (2) having a raw air inlet (4), a pure air outlet (5), and an annular filter element (3) which is arranged in the filter housing (2) and through which air can flow in a radial manner from the outside towards the inside. The filter element has a first end disk (10) on the axial end thereof, said disk has an opening (12) by which means the pure air outlet (5) communicates with the inside (8) of the annular filter element (3). The purpose is to reduce the influence of a secondary air induction on the fresh air supply of the internal combustion engine. To this end, the filter housing (2) has a secondary air outlet (6), on the pure air side, and the annular filter element (3) has a second end disk (11) on an axial end opposing the first end disk (10). The second end disk has at least one opening (17) by which the secondary air outlet (6) communicates with the inside (8) of the annular filter element (3).