The rehabilitation and the maintenance of masonry arch bridges is a current necessity for the infrastructure owners. In fact, masonry bridges represent a large portion of the existing bridges in the world's road and rail networks. In this contribute, external post-tensioning system has been used to strength single span pre-damage masonry arches. The specimens, that represents in scale a typical geometry of the Italian single-span railway masonry bridges, was strengthened with a post-tensioned cable system anchored at the arch intrados and then it was tested with a cyclic concentrated eccentric vertical load. The strengthened masonry arch shows a load bearing capacity greater respect to that in the undamaged condition.The rehabilitation and the maintenance of masonry arch bridges is a current necessity for the infrastructure owners. In fact, masonry bridges represent a large portion of the existing bridges in the world’s road and rail networks. In this contribute, external post-tensioning system has been used to strength single span pre-damage masonry arches. The specimens, that represents in scale a typical geometry of the Italian single-span railway masonry bridges, was strengthened with a post-tensioned cable system anchored at the arch intrados and then it was tested with a cyclic concentrated eccentric vertical load. The strengthened masonry arch shows a load bearing capacity greater respect to that in the undamaged condition.