Iron ore concentration through flotation represents an important application of reagents in mineral processing. Nowadays all Brazilian iron ore concentrators use starch as iron oxides depressant. This study evaluated the application of other depressants, which are commonly used in other flotation systems. Six carboxymethylcelluloses, three lignosulphonates, one guar gum, and four humic acids samples were investigated in the reverse cationic flotation. Laboratory flotation tests showed that only two polymers (one carboxymethylcellulose and guar gum) reached the same performance as starch. The superior performance of these reagents was due to the presence of the glucopyranose ring. The use of polymers blends led to promising results. (C) 2010 Elsevier Ltd. All rights reserved.