A study of the stalled flow performance of multistage axial compressors is presented. A proposal is made regarding the form of axisymmetric pumping performance in stall (which is a requisite of current rotating stall models) over the entire compressor flow range, including reversed flow. It is also shown that the axisymmetric performance can rise above the measured stall point pressure rise, thus indicating greater unstalled pressure rise potential. A simple two-dimensional reversed flow model is presented, and is shown to be in reasonable agreement with available high backflow compressor data. The model predicts that the blade stagger angle greatly influences the reversed flow characteristic. Calculations are also carried out applying this axisymmetric characteristic to the rotating stall model of Moore.