A process gas for use in laser welding with a laser beam focused onto the work piece to be welded. The inventive process gas comprises helium, nitrogen, and at least one of carbon dioxide in an amount of up to 40% by volume, and oxygen in an amount of up to 30% by volume. The gas may comprise not more than 85% by volume of helium. Also disclosed are methods of laser welding using the inventive process gas. The invention is suitable for laser welding of low-alloy steels and coated, especially zinc-coated steels.