Experiments to evaluate the milling performance, hence the relative cost effectiveness index of selected grinding media were conducted in a laboratory scale ball mill. The five types of grinding mill balls studied were eutectoid steel, low alloy steel, medium chromium cast iron, cast semi-steel and unalloyed white cast iron. The results obtained show that the heat-treated medium chromium cast iron ball possess a superior combination microstructure, wear resistance, and despite its high price per tonne, cost effectiveness. (C) 2003 Elsevier Ltd. All rights reserved.