The authors describe the fundamental nature of the flow field and the influence of the end winding's porosity within the end region of a TEFC induction machine. A simulated end winding of simplified geometry was used for the investigation. Effects upon the flow field and ventilation losses are reported. Owing to the physical size and positioning of the end winding, changes in porosity produce large changes in flow rate and circulation affecting the flow rates by varying the flow resistance at the fan outlet and affecting the amount of flow through the end winding itself. This affects all aspects of the flow field by altering the angular momentum in the flow circulation. The changes in flow rate and circulation are also reflected by large changes in the ventilation losses.