['Patients undergoing in vitro fertilization and embryo transfer (IVF-ET) failures show an increased incidence of antiphospholipid antibodies (aPL) in their blood. The physiological manifestations of aPL in this patient group are nonetheless controversial. Pathological effects of aPL on embryos in vitro have been documented. We questioned whether aPL if found in follicular fluids (FFs) could result in embryonic damage.', 'Blood from 44 patients with three or more IVF-ET failures were tested by enzyme-linked immunosorbent assays (ELISA) for the presence of immunoglobulin (Ig)G, IgM and IgA aPL. Both the 29 aPL-positive and 15 aPL-negative patients gave permission for FF collection during their next IVF-ET attempt for additional aPL determinations.', 'Patients with no aPL in their blood, had no aPL in their FFs. Patients with IgG and/or IgM aPL in their blood had IgG but not IgM in their respective FFs.'] Are igG-antiphospholipid antibodies in follicular fluid of IVF-ET patients related to low fertilization rate of their oocytes?