Separable slide fasteners are manufactured from an elongate slide fastener chain (10) composed of a pair of slide fastener stringers (11, 11) having rows of coupling elements (12,12) alternating with element-free portions (13,13) having substantially U-shaped recesses (14, 14) defined in inner edges thereof. The elongate slide fastener chain (10) is fed under tension along a longitudinal path, and the slide fastener stringers (11, 11) are separated from each other. Then, an insertion pin (24) is attached laterally to the inner edge of one of the element-free portions (13), and a box pin (27) is attached laterally to the inner edge of another element-free portion (13) confronting said one element-free portion (13). The insertion pin (24) and the box pin (27) which are laterally aligned with each other are threaded through a slider (32) until certain coupling elements (12, 12) of the slide fastener stringers (11, 11) are interengaged. Then, a box (34) is attached to the box pin (27). An elongate product (46) composed of joined separable slide fasteners may be sewn to successive garment fabrics (48), or may be cut off into individual separable slide fasteners (45).