Abstract: An air intake muffler for a heater, especially a motor vehicle heater, with a hollow body (7) of sound-absorbing material which is surrounded by a muffler chamber (2) and is penetrated by a cavity (8) which is flush with an inlet connection (9) and an outlet (10) of the muffler chamber (2) which can be connected to an air intake opening of the heater. To reliably prevent water or moisture from penetrating into an assembly downstream of the muffler (1), it is provided that the muffler chamber (2) is downstream of a water separator which has a water separation chamber (3) with at least one air intake opening (20 to 23) in its wall located laterally offset relative to the inlet of the muffler chamber (2) and which is separated from the muffler chamber by a deflector wall (24 to 27) which prevents direct flow from the air intake opening to the inlet connection (9).