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 antibod...