An arc augmented laser welding apparatus has a welding head (10) which comprises a housing (14) a focusing system in the housing for focusing a laser beam through a laser opening in the housing onto a workpiece and a plasma torch nozzle (28) through which a plasma arc is established between an electrode (22) and the workpiece. A first power source (44) applies a high voltage across the electrode and nozzle to strike a pilot arc which is then sustained by power from a second source (42). A third power source (40) applies a high amperage signal to strike the main plasma arc between the electrode and the workpiece. The nozzle has a tip (33) which is adapted to constrict the plasma arc and restrict its impingement on the workpiece. The nozzle and the focusing system are arranged to cause the focused laser beam and the constricted plasma arc to impinge on the workpiece at predetermined relative positions which may coincide or may be slightly spaced apart. The power sources and the laser beam are controlled by a microprocessor in accordance with a predetermined programme in dependence on the type and thickness of material to be welded.