Abstract: An apparatus and method for on-line pretwisting of welding wire. A spindle member is rotatably mounted within a housing, which includes an inlet for receiving two or more strands of welding wire. A wire advancing mechanism is provided within a cavity formed in the spindle member immediately downstream of the housing inlet, for advancing the strands of wire through the spindle member and the housing. The spindle member is rotatable about a twisting axis relative to the housing. Upon simultaneous operation of the advancing mechanism and rotation of the spindle member, twisting is imparted to the wire strands. The advancing mechanism feeds the twisted wire strands through a guide tube, which has its outlet positioned immediately upstream of a welding head. The twisted welding wire is fed through the guide tube outlet into the welding head for use in a welding operation.