Head harness form gas mask consists of several pieces of biaxially stretchable elastic fabric stitched together to provide a concave configuration in the relaxed state. The harness is shaped and sized to fit a range of normal human heads by stretching over the back and top of the head. The forward edge of the harness has a number of tongues of the elastic fabric that attach to a gas mask. The preferred material for the harness is a 280 denier bare spandex power net fabric that has a flat load versus elongation curve. A gas mask fitted with the harness applies a uniform pressure within the comfort range on the face of the wearer without significant adjustment of the harness, despite wide ranges in the head size and configuration of the wearer.