Flotation is a difficult process to run efficiently. One way to make flotation performance better is to improve cell level control. However, controlling pulp levels in flotation cells is a complex control task because of strong interactions between the levels in flotation cells. Therefore advanced controllers are needed to give good level control. This paper deals with a model of six flotation cells in series. Simulations are performed to compare different control strategies. Four control strategies are considered: one SISO controller and three different MIMO controllers including a new multivariable controller. It is shown that level control performances of the MIMO controllers are significantly better than that of the classical SISO controller. (C) 2003 Elsevier Ltd. All rights reserved.