A fastener for use in attaching a button to a garment or a piece of fabric and a fastener clip including one or more of said fasteners. In a preferred embodiment, the fastener comprises a U-shaped flexible filament and a pair of transverse feet, the transverse feet being disposed at opposite ends of the U-shaped flexible filament. The U-shaped flexible filament is generally rectangular in cross-section. The width of the filament is substantially uniform over its length whereas the thickness of the filament is greatest in its arcuate region (to maximize the strength of the fastener) and least towards the feet. Because of its U-shape, the filament is permitted to extend between adjacent button holes, thereby creating the appearance of thread. The transverse feet, which extend parallel to one another and perpendicularly to the plane of the filament, are sized and shaped both to fit through a button hole and, once inserted through the button hole and an underlying garment, to securely engage the underside of the garment. To minimize contact with a person's skin, the feet of the present fastener are preferably shorter than the transverse bars of existing button fasteners and are preferably comparable in overall size to a knot of thread used to secure a button to a sheet of clothing material. In addition, the feet preferably have rounded ends, a fiat top surface, and a contoured bottom surface to minimize contact with, and hence irritation of, a person's skin.