Genital tract infection and inflammationhavebeenassociatedto8-35%ofmaleinfertilitycases.E.colicausesagglutination of human spermatozoa and thus, leading to infertility. This study aim to evaluate if the negative influenceofEscherichiacoli on the motility of human spermatozoa is a consequence of E. coli adhesion or some soluble factor from E. coli are involved. Highly motile preparation of spermatozoa from normozoospermic patients were obtained by ‘swim up' procedure the. Study was carried out in three parts. Motility parameters were analysed by light microscopy and Nomarski differential interference contrast microscopy directly, and after 30 min; 2, 4, 6 hs and overnight after inoculation. In The second series of experiments, bacterial replication was inhibited by addition of fiveantibioticsamoxicillin,ciprofloxacin,erythromycin,gentamycinandpenicillin G. The effect of E. coli culture filtratesonspermmotilitywasinvestigated.FinallyInathirdseries,E.coligrowthwassuppressed by heating at high temperature (100 oC) for 30 min. E. coli decreased the sperm motility and viability by agglutination immediately after inoculation and effect increases as the time of incubation Period increases.Amazingly , both culture media in which E. coli growth was inhibited by either (antibiotic and heating), was not able to cause any change in motility and viability. Further more, completion of incubation at Period up to 6 hs the percentage of motile spermatozoa left is 11% that is very low as compared to control. This shows that E. coli may be carrying some adhesion sites through which it binds to human spermatozoa and causes agglutination. And hence infartility