To determine the incidence and the clinical significance of antisperm antibodies (ASA) in cervical secretions in an unselected subfertile population, cervical mucus samples of 192 patients with long-standing infertility were screened by means of the indirect mixed antiglobulin reaction (MAR) test allowing differentiation for immunoglobulin (Ig)A and IgG in a parallel test setting. In addition, the indirect MAR IgG test in cervical mucus was evaluated by means of IgG coated latex particles instead of sensitized erythrocytes as the indicator system. All cervical mucus samples were taken under standardized conditions. Results of ASA determination were related to microbial findings in the cervix and the outcome of sperm-mucus interaction testing in vivo and in vitro, and the subsequent fertility in a prospective study. The total incidence of cervical mucus ASA within this population was low (< 2%). A significant correlation was found between sperm antibodies of the IgG and IgA class and of IgG ASA, determined with the standard MAR and testing with latex microspheres as indicator particles. Results were not influenced by microbial colonization of the cervix and were not markedly related to lymphocytes subset testing. All ASA positive women had a negative outcome of the post-coital test, but the majority of negative post-coital tests was not caused by local mucus antibodies of the IgG and/or IgA class. In patients with positive indirect MAR testing in cervical mucus, there was no pregnancy within an observation period of > 12 months. In conclusion, the results indicate the ASA in cervical secretions are not frequent but nevertheless are a severe cause of infertility when present.(ABSTRACT TRUNCATED AT 250 WORDS)