Abstract: A system for introducing an elongated spinal rod comprising a bone fastener having a head, the head including a top end, a bottom end, and a pair of side walls connected at the bottom end defining an elongated U-shaped channel having a first longitudinal axis and a top opening located at the top end. The top opening and the channel further define a passageway configured for receiving the spinal rod and each side wall further defining a first end face and a second end face, the second end face opposite the first end face. A bone engaging element extends from the bottom end of the head for anchoring the bone fastener to the bone. The system further comprises a tool for introducing the rod into the U-shaped channel. The tool includes a first member having a distal end and a proximal end. The distal end is configured for guiding the rod through the passageway to introduce the rod into the U-shaped channel through the top opening.