A side guide for guiding and/or holding cargo items, in particular containers and/or pallets, in an aircraft, comprising a fastening rail extending in the longitudinal direction (v), at least one side guide device, which can be fastened to the fastening rail in the longitudinal direction (v) at different positions (A, B, C, D) and at least one first and at least one second fastening device for fastening the side guide to a cargo deck of the aircraft, in particular in a perforated rail. The first fastening device engages around the fastening rail and/or engages in the fastening rail in such a way that the first fastening device can be displaced in the longitudinal direction (v), in particular relative to the second fastening device.