It has been suggested that patients with clinical features suggestive of antiphospholipid syndrome but being lupus anticoagulant (LA) and anticardiolipin (aCL) negative, should be tested for antibodies to beta(2) glycoprotein-I (abeta(2)GP-I), a protein involved in the binding of antiphospholipid antibodies (aPL) to phospholipid surfaces. This was investigated in the present study where a total of 385 women aged </=40 years were included. Of these, 175 were experimental subjects and 210 were controls. The former comprised the following two study groups: 100 spontaneous recurrent aborters (group one), and 75 patients with repeated failure of embryo transfer (group two). Controls included three groups of women: 100 normal healthy parous women with no previous abortion (group three), 60 infertile patients achieving a live birth with their first in-vitro fertilization (IVF)/embryo transfer attempt (group four), and 50 patients with recurrent abortion who tested positive for aPL (LA and/or aCL) (positive controls, group five). Only one patient among recurrent aborters (group one) tested positive for abeta(2)GP-I. All women in groups two, three and four were negative for abeta(2)GP-I screening. As expected, prevalence of patients testing positive for abeta(2)GP-I was significantly higher in group five than among the other groups of patients (P < 0.001). No differences were observed regarding the prevalence of abeta(2)GP-I positive sera in the subgroup of patients having aCL and those having the LA in group five. It is concluded that abeta(2)GP-I screening in first-trimester recurrent abortion or in failure of implantation after IVF is not warranted in patients without aPL as detected by standard antiphospholipid assays.