This article presents a brief record of the major alloy developments in cast irons, together with the approximate dates of their introduction in the first 50 years of the 20th century. This was a period of immense activity and development in the field of new materials and laid the foundations for much of the alloy cast iron used at the present time. Much literature exists from which a selection from the most important items is included, though this is unlikely to be complete and further study will be rewarding.