Preeclampsia (PE) is a multisystem pregnancy complication that is the leading cause of maternal and perinatal morbidity and mortality. Today, a large body of data has been accumulated, suggesting that an abnormal maternal immune response in PE is manifested, among other things, as a change in the functional activity of the monocyte-macrophage system, the most important unit of innate immunity. The cause of abnormal placentation underlying PE, especially early PE, may be dysfunction of placental immune cells, namely macrophages. The macrophages are one of the main cellular constituents of the decidua, the maternal component of the placenta, and also play an important role in the development of the fetal part of the placenta, per se being one of the first immune cells of a baby. Depending on their functional state, the macrophages can either stimulate or suppress inflammation, angiogenesis, and the proliferation of neighboring cells. According to the concept of binary polarization, there are two states of macrophages: classically activated macrophages (M1) produce proinflammatory cytokines and reactive oxygen/nitrogen species. The other type of macrophages (M2) produces anti-inflammatory cytokines and is involved in the elimination of inflammation. Conclusion: Turning to the key differential markers of macrophages, this review attempts to summarize the current data on the functioning of the monocyte-macrophage system in physiological pregnancy and PE. © A group of authors, 2022.