The effects of reprocessing by injection molding on the structure and properties of poly(ether imide) (PEI) were studied. The chemical structure of PEI does not change after reprocessing. However, the weight-average molecular weight decreases after the first and the second injection cycles, after which it stays constant. Despite the harsh conditions used, the thermal resistence and the small strain mechanical properties were unaffected by the application of successive injection molding processes to the 100% regrind PEI specimens. The tensile ductility and energy at break showed a decrease parallel to that of the molecular weight. However, the Izod impact strength was constant, probably due to the differences in strain rate and mode of deformation between the tensile and impact tests.