Abstract The aim: The aim of the study was the analysis of antiphospholipid syndrome frequency in Polish women with pregnancy loss. Material and methods: We analyzed 352 women with average age of 31.4 (±4.3) who experienced one or more pregnancy losses. Patients from 5 University centers: Poznań, Białystok, Lublin, Wrocław and Bydgoszcz were divided into 3 groups. In the 1st group there were 150 women with recurrent early pregnancy losses before 10 weeks gestation, in the 2nd group we included 160 women with late pregnancy losses, in the 3rd group we analyzed 42 women with labor complicated by preeclampsia or placental insufficiency within or before 34 gestational week. All 352 women were screened for the presence of anticardiolipin antibodies (aCL), anti β2glikoprotein I (aβ2GPI) and lupus anticoagulant (LA). The first two antibodies were investigated with ELISA test and the last one with APPT based test. Only the second positive result qualified patients as antiphospholipid antibody (aPL) positive. Antibodies against cardiolipin and β2glicoprotein I were analyzed in three classes – IgA, IgG and IgM – where the laboratory criteria of positivity were titers above 40 unitsU/ml or above 99 centile. Results: 13 patients (3.69%) in the screened population of 352 women met the criteria of the antiphospholipid syndrome. The frequency of APS in women with early and late pregnancy losses were 1.33% and 6.25%, respectively. The most common antibody found was lupus anticoagulant (LA). In 3 women with late pregnancy loss all three antibodies were found. In women with premature deliveries complicated with preeclampsia and/or placental insufficiency the frequency of APS was 2.58%. Conclusion: 1. Screening of antiphospholipid syndrome should be routinely performed in women with late pregnancy loss 2. We can conclude that APS is rarely found in women with pregnancy loss before 10 gestational week