In a woven slide fastener stringer of the type which comprises a row of successively interconnected elongated loops of a plastic filament woven into a longitudinal edge of a stringer tape woven of foundation warp and weft threads, and a pair of groups of upper and lower binding warp threads extending respectively over and under the loops and interwoven with the foundation weft thread, the improvements comprising a gap-filling warp thread extending parallel with and between an outermost one of the upper binding warp threads and the next adjoining upper binding warp thread and also between an outermost one of the lower binding warp threads and the next adjoining lower binding warp thread, and passing alternately over and under the foundation weft thread, thereby tensioning the latter thread to sink substantially halfway between the upper and lower legs of each adjacent pair of loops. Preferably, the outermost upper and lower binding warp threads are disposed in registry with each other to make the foundation weft thread lie substantially perpendicualr to the plane of the fastener stringer between the two outermost binding warp threads. The row of loops thus woven is stably secured in place against angular displacement and held at the proper pitch with respect to individual adjacent loops.