In order to reveal the effect of reuse solution and the hemodialysis environment on the stability of high flux polyamide hollow fiber membranes, mechanical tests, surface and X-ray diffraction studies were performed on both virgin 17S high flux polyamide hollow fiber and used-processed 17S high flux polyamide hollow fiber membranes. Used fibers were left in 4% formaldehyde solution for 14 hours and then in 5% sodium hypochloride (bleach) solution for 6 hours in order to disinfect the membrane for the reuse idea. Tensile tests performed on both virgin and used-processed fibers reveal that toughness and ductility of the used-processed fibers are lower than the virgin ones. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies performed on virgin and used-processed fiber visualized the morphological changes. Rough surface with defects and cracks was seen in used-processed fiber, whereas a smoother surface morphology was seen in virgin fibers. Alterations in pore morphology and the size of the pores became greater in used processed fibers. Cracks, merging of pores and also more defects were visualized in used-processed fibers. Thus, easy crack initiations and easy propagations were expected in used-processed fibers which were also confirmed by tensile test experiments. In addition to these mechanical and surface studies experiments, X-ray diffractometry studies also revealed the changes in the structure of the used-processed fibers. New or growth of the existing phases and orientations were observed in used-processed fibers. This study showed that dialysis environment caused structural changes on membranes which may cause clinical complications.