Although sperm-associated antibody could impair fertility through various mechanisms, the results of follow-up studies do not uniformly confirm that pregnancy rates are lower when one of the infertile partners demonstrates antibody to spermatozoa. We conducted a prospective double-blind cohort comparative analysis in which antibody assay results were not available to physicians or patients for clinical management. The diagnostic protocol included mid-luteal progesterone, semen analysis, hysterosalpingogram and laparoscopy. The serum of each partner was assayed by immunobead testing, tray agglutination testing and a gelatin agglutination test. Data on relevant clinical characteristics and events during follow-up were collected prospectively. Among 471 couples in whom both partners were evaluated, 42 (8.9%) tested positive for anti-sperm antibodies by one or more assays, including 38 (8.1%) male partners and 6 (1.3%) female partners. The number of conceptions was 118/429 (27.5%) in antibody negative couples, 9/38 (23.7%) in male partner-positive couples and 1/6 (16.7%) in female partner-positive couples. With proportional hazards analysis, antibody status in either partner was not a significant independent predictor of time to pregnancy.