A new enzyme-linked immunosorbent assay (ELISA)-based test (Zer, Jerusalem) has allowed us to show the presence of antisperm antibodies (1:32 to 1:64) in the blood of 14 (33%) of 32 patients undergoing in vitro fertilization and embryo transfer (IVF-ET) under gonadotropin stimulation. Observation of the morphology of fertilization in eight patients with and seven patients without antisperm antibodies has shown a significant association (P less than or equal to 0.025, Fisher exact probability test) among the cumulus/corona coagulation, the absence of fertilization, and the presence of these antibodies. Cumulus/oocyte complex washing and/or enzymatic cumulus removal are considered as elective interventions in the case of antisperm immunity. Each patient entering an IVF-ET program should have the antisperm antibody assay performed as a preliminary screening.