The paper uses the concept of severance energy in the laser cutting of mild steel to compare process arrangements. This gives a relative measure of cutting efficiency. Severance ener- gies have been collated for various published works and the results compared. These results show a marked sensitivity for CO2 laser cutting in CW mode. The laser operator when presented with a particular job must assess the various laser-cutting parameters in order to determine how to set the laser controls to produce an optimum cut. One of the key cutting parameters is cutting speed, and in particular its variation with thickness of material being cut. The relation- ship between these two parameters can be best expressed in terms of the energy required per unit area of material severed by the laser beam or severance energy. Although the efficiency of the use of the energy delivered by a laser beam depends on various process parameters, the concept of severance energy enables comparison of one particular process arrangement with another - it is therefore a relative measure of cutting efficiency. Although severance energies have been collated from two sources by Steen (1), there has been no other independent comparison with related published work. In this paper, the results of a comparison of severance energies from a variety of published work is presented. This will demonstrate the commonality of results that have been obtained for the reactive gas cutting of mild steel using a CO2 laser operating in continuous wave (CW) mode.