Abstract: Protein purity of the final crystalline product is important in both industrial crystallization and in growth of high quality protein crystals essential for X-ray diffraction structural studies. Growing diffraction quality crystals is a major challenge, as crystals invariably tend to incorporate impurities during growth which can detrimentally affect the quality of the diffraction data. In earlier studies examining the distribution of a homologous protein in the host hen egg white lysozyme (HEWL) crystal, growth conditions were found to strongly affect impurity partitioning. Based on these insights, our recent efforts on re-crystallizing commercial HEWL are interpreted and a protocol for re-crystallization suggested. This protein, as obtained was not pure enough for fundamental nucleation and growth kinetic studies. We report various protocols aimed at minimizing the incorporation of impurities during the re-crystallization process with a resultant improvement in crystal purity.