A filter insert for the filtering of the fresh air supplied to a motor vehicle interior has an accordion-folded filter element which is self-supporting. Lateral strips coated with an adhesive are provided on the faces which extend on the left and on the right. On the faces which extend in parallel to the folding, angle strips are arranged whose first leg extends along at least three fold edges. The filter element is surrounded along the faces by a foamed-material sealing.
