Abstract: A patch test plaster having at least one active substance receptacle arranged on a backing film, having a highly elastic backing film which is made of polymeric material, is impermeable to liquid water but permeable to water vapour, and is releasibly connected on the surface facing away from the skin to a supporting sheet and is provided on the surface facing the skin with an adhesive layer which is in turn covered by an at least two-part detachable protecting layer before application of the plaster, is characterized in that the protecting layer has a hinge-like connection on two opposite edges to the supporting sheet.