A protective sleeve for small portable electronic devices, in particular mobile or wireless telephones, is disclosed, comprising at least one strap-like elastic loop, which at least partly surrounds the external circumference of the device when applied to the device. According to the invention, only one loop (2) is provided which is a highly elastic tubular ring, the material, diameter, height and wall thickness of which are arranged such that, when tightly applied to the device, the external circumferential cover of the device is covered and the end edges of the loop are drawn elastically inwards on both front faces (5) of the device and lie thereon in the form of narrow strips (6), forming a frame.