We know that antisperm antibodies can cause infertility. We studied the prevalence of the immune response against spermatozoa in infertile couples using immunobead test. 16.2% of the men were autoimmune and 7.3% of the women isoimmune. Both partners were immune in 1.6% of the couples. We also studied the degree of impairment of sperm penetration into cervical mucus in couples in which one of the partners exhibited immunity and we found that generally it correlates with the proportion of sperm exhibiting surface-bound immunoglobulins. In some cases the sperm penetration into cervical mucus was normal in spite of immunization. So other mechanisms of interference should be explored. We found a significant difference (p less than 0.02) in the conception rate between immune and non immune couples (19.3% vs 42%). The pregnancy outcome of immune couples was favorable only in 50% of the cases.