Amongst the diverse fluid velocities establishing the existence of the different fluidization regimes, only minimum fluidization velocity has been extensively studied. Although an increasing number of communications have been devoted in the last decade to circulating fluidized beds, the prediction of the velocities over which bubbling, turbulent and fast fluidization exist is still difficult. Even the existence of the different fluidization regimes is not perfectly established. In this communication, the diverse correlations available for the calculation of u(c), u(k) and u(tr) are analysed and compared to experimental data. Conclusions are derived about their adequacy, and a simple map is proposed for the operating conditions over which each fluidization regime exists.