Previous independent studies have indicated that abnormally low parameters of sperm DNA integrity and sperm membrane integrity correlate to reduced fertility due in part to implantation disorders. The purpose of our study was to evaluate the relationship between sperm plasma membrane functional integrity assessed by the hypo-osmotic swelling test (HOST) and sperm DNA integriy test assesed by DNA fragmentation index (DFI). Semen samples from 102 random patients were evaluated in terms of standard semen parameters and assessed by DFI and HOST. Both tests showed a significant correlation to standard semen parameters (p<.05). In addition, patients with abnormal HOST results had a higher likehood of a subnormal or abnormal DFI result (p<.001). Our results suggest that a common sublethal insult may manifest as abnormalities in both the nucleus and the plasma membrane that act at the implantation and/or subsequent levels of development rather than at the fertilization stage.