A watertight slide fastener stringer comprises a series of coupling elements mounted on a watertight stringer tape along a longitudinal edge portion thereof. Each coupling element includes a pair of upper and lower halves or members disposed one on each side of the stringer tape and joined by at least one integral connector extending through the stringer tape. Each of the coupling element members has a coupling portion including a support portion disposed on a thickened sealing member which is disposed on the longitudinal tape edge, a neck portion on the support portion, and a coupling head on the support portion integral with the neck and projecting beyond the thickened sealing member. The support portion and the neck portion jointly define therebetween a pair of recesses opening away from the plane of the stringer tape for receiving therein the coupling heads of mating coupling elements. A layer made of a cured adhesive material is disposed on each side of the stringer tape at least around the integral connector to prevent water leakage between opposite sides of the coupled fastener stringers.