A device for ventilating and aerating a fuel tank includes a tank shut-off valve and two tank pressure control valves. One of the tank pressure control valves opens in response to an overpressure in the fuel tank and the other one of the tank pressure control valves closes in response to a negative pressure in the fuel tank. A valve unit which is formed from one or multiple of the valves is mountable vertically or horizontally and has a fuel connection which communicates with the fuel tank and a filter connection which communicates with an activated carbon filter. The two connections are generally oriented parallel and point downwards in vertical mounting position of the valve unit and in sideward direction(s) in horizontal mounting position of the valve unit and are arranged at or near the bottom side of the valve unit.