A filter system for intake air of an internal combustion engine has a housing with a cover. A filter element is arranged in the housing. An inlet feeds a medium to be filtered into the housing and an outlet discharges the medium from the housing. The filter element has a filter body with first end face and opposite second end face. The filter element has an open first end plate at the first end face and a second end plate at the second end face. A support tube is arranged concentrically about a longitudinal axis in the housing and attached with a first end to the housing. The support tube is arranged in the interior of the filter element and radially supports the filter body. The second end plate rests on the second end of the support tube and on an inner cover contour of the cover with anti-rotation action.