Abstract: A slotted core type optical fiber ribbon cable includes a cylindrical rod having a plurality of helical slots in its exterior surface. A slot holds a stack of optical fiber ribbons each having a planar array of optical fibers therein. The pitch of the helical slot is selected so as to allow total optical fiber stranding strain .epsilon. of the edge fibers in the ribbon to be at least 0.05% and compression .epsilon..sub.e on the middle optical fiber or optical fibers in the ribbon to be less than about 0.03%. The magnitude of the slot pitch is selected to be in the rangeP.sub.c <P<P.sub.s, withP.sub.c =(-6.718+76.094W.sub.r)+(-2.0467+0.33014W.sub.r)R.sub.r andP.sub.s =(340.92+1.3495W.sub.r +6.8775W.sub.r.sup.2)+(4.5417-0.07796W.sub.r -0.037W.sub.r.sup.2)R.sub.r,where P is the slot pitch, W.sub.r is the width spanned by the optical fibers in the ribbon, and R.sub.r is the radial distance between the rod longitudinal axis and the midpoint of the width spanned by the optical fibers in the bottommost ribbon.