['To determine if fertilization antigen (FA)-1 will remove autoantibodies from the surface of sperm cells of immunoinfertile men by immune adsorption and permit an increased acrosome reaction (AR).', 'Prospective analytic study.', 'University medical center.', 'Men from 18 infertile couples with autoantibodies present on their spermatozoa.', 'Sperm samples after processing were examined for antibody binding and AR before and after adsorption with control medium or FA-1.', 'Sperm-bound antibody was assessed by the immunobead assay (immunoglobulin [Ig] A and IgG) and the AR by induction with ionophore A23187.', 'Adsorption with FA-1 compared with control medium increased immunobead-free swimming sperm an average of 50% and 76% for IgA and IgG antisperm antibodies, respectively, with 78% and 100% of the 18 semen specimens increasing significantly. The AR rate increased an average of 10.3% compared with control medium and showed improvement in 78% of the sperm samples after FA-1 adsorption.'] Does fertilization antigen-1 remove antisperm autoantibodies from spermatozoa of infertile men and results in increased rates of acrosome reaction?