A pitch transition wire guide apparatus for use in wire harness fabrication machines includes a plate member having a wire engaging edge and a corresponding number of open-ended wire guide channels, each extending inwardly from the edge to a closed end. The closed ends of said channels are spaced apart by a centerline spacing different from the centerline spacing of the open ends in said edge. The plate is reciprocably moveable between a first position wherein the open ends are in surrounding engagement with the wires adjacent the edge and a second wire-receiving position wherein said wires are disposed at the closed ends. The guide includes actuation means for moving the plate member between said first and second positions. Actuation of the wire guide causes movement of the wires within their respective channels to alter the centerline spacing thereof. The wire guide is useful for making smooth continuous transitions between production runs of different pitch wire harnesses. It is also useful for making pitch transition wire harnesses wherein a common group of wires are terminated to at least two connectors, each one containing terminals spaced apart at different centerline spacings.