Cast irons in grate bars and furnace doors traditionally have been compared principally on their comparative growth properties. Recently, in an attempt to accumulate experimental data which might be more useful in predicting the serviceability of cast irons at elevated temperatures, tests have been conducted measuring the oxidation resistance of some of these materials. These tests are described in this article, with results on plain and low alloyed cast irons and highly alloyed austenitic cast irons in several environments. Some description of how cast iron deteriorates with growth is also included. The various typical applications of simple cast irons, low alloyed cast irons, austenitic cast irons and the ductile varieties of austenitic cast irons are described here with the engineering reasons for their economical use in high temperature service.