Laboratory flotation tests were conducted to investigate the role of pH, zinc sulphate and potassium metabisulphite in the flotation of galena and marmatite in the Broken Hill orebody. Marmatite was depressed under alkaline conditions alone, however the addition of the two depressants, either individually or combined, resulted in the greatest selectivity. The use of zinc sulphate under alkaline conditions resulted in good selectivity whilst maintaining a high lead recovery. The addition of potassium metabisulphite under alkaline conditions reduced zinc recovery, but high additions reduced lead recovery. The addition of both depressants at alkaline pH produced the best result, with a lead concentrate of 72.6% at 98% recovery with less than 4% zinc recovery. The overall aim of the study was to minimise the flotation of marmatite into the galena rougher concentrate, which was achieved under the conditions given above. (C) 2005 Elsevier Ltd. All rights reserved.