It is known that the rheological behaviour of mineral slurries affects their processing. However, in addition to controlling the transportation of slurries around processing circuits, rheological behaviour also influences separation processes such as flotation. The rheological behaviour of mineral slurries is indicative of the level of inter-particle interaction or aggregation. In fact, rheological studies can be used as a direct approach to investigating such phenomena, thereby furthering our understanding of inter-particle interactions and potentially of bubble-particle interactions in mineral slurries. Although the impact of rheology in unit operations such as grinding and slurry transport has received considerable attention, this has not been the case for flotation. The pathways by which the rheology influences the flotation performance are not yet fully understood. These pathways may include various mechanisms occurring in the pulp and froth phases. However to date, little work has been done on froth rheology. Measuring the rheological properties of mineral slurries is also difficult since particles tend to settle during measurement. Finding a proper practical way for taking such measurements remains a challenge for research. In this paper the importance of rheology in mineral flotation is reviewed, and the gap of knowledge in this area is highlighted for further research. (C) 2012 Elsevier Ltd. All rights reserved.