Techniques for the treatment and production of SG iron in both the UK and the USA have changed considerably over the past 37 years. The article reviews some of the more important treatment processes. They include overpour, sandwich, trigger, tundish, injection, stirring, plunging, pressure vessel, SKB, Pont-a-Mousson, invertible pressure, Fishcher, magnesium nitride, gas, electrolytic, holding, T Nock, Flotret and Im Mold processes.