The HELLP syndrome (H = hemolysis, EL = elevated liver enzymes, LP = low platelets) is a pregnancy complication which affects 10-20% of cases of severe preeclampsia.The article is a review of the literature.Approximately 70% of HELLP syndrome cases occur before delivery, 15% as early as in the second trimester, the remainder after delivery. The classical HELLP syndrome is characterised by abdominal pain, pathological liver tests and low platelets. However, some cases are atypical; hypertension and abdominal pain may both be absent. Genetic as well as immunologic factors are involved in the pathogenesis. There is an imbalance in the coagulation process in the placenta. Activated leukocytes and macrophages induce production of cytokines that may reach the general circulation and cause endothelial dysfunction. In the HELLP syndrome fibrin deposits are also found in the vessels and in the liver sinusoides.A mother with a classic HELLP syndrome should be delivered after stabilisation of the clinical condition. A partial HELLP syndrome can be observed. Treatment with corticosteroids is beneficial.