['To evaluate the effect of VIC-1 and ZAP-7 antihuman sperm monoclonal antibodies on in vivo fertility in the mouse.', 'A randomized blinded study using a mouse model.', 'University-based laboratory.', 'B6CBAF1 mice (n = 6 per experimental group).', 'Antisperm antibodies were administered intravaginally to female mice before mating. Control mice received no treatment, saline, or nonspecific antibodies. Number and viability of preimplantation embryos were determined by microscopic observation. Mouse sperm, oocytes, and normal preimplantation embryos were used in indirect immunofluorescence assays with antisperm antibodies. The effect of antibody treatment on sperm motility and vitality was evaluated.', 'Antigen expression, sperm motility and vitality, number and viability of embryos.', 'ZAP-7 antibody recognizes a sperm antigen expressed in zygotes and early preimplantation embryos. Passive immunization with ZAP-7 increases embryo mortality significantly (more than 40% above controls). Passive immunization with VIC-1 has no deleterious effect.'] Does passive immunization with antisperm monoclonal antibody ZAP-7 increase preimplantation embryo mortality in the mouse?