Defined by the association of hemolysis, hepatic dysfunction and thrombocytopenia, the Hemolysis, Elevated Liver enzyme, Low Platelets (HELLP) syndrome can complicate preeclampsia and worsen maternal and fetal prognosis. It can be diagnosed in the immediate postpartum (30%) or in the absence of preeclampsia (10-20%). Clinical diagnosis can be difficult because there is no specific symptom. Abdominal pain or vomiting during the third trimester must lead to think about this diagnosis. Biological criteria are well defined: hemolysis by the presence of schistocytes, increased serum total bilirubin >12 mg/L or LDH >600 IU/L, hepatic dysfunction by increased transaminases and thrombocytopenia by a platelet count <100,000/microL. The evolution of those parameters is a major prognostic factor. With the HELLP syndrome, maternal morbidity is dramatically increased compared to isolated preeclampsia with complications such as eclampsia, placental abruptio, disseminated intravascular coagulation, pulmonary edema, acute renal insufficiency, subcapsular liver hematoma. The management of a HELLP syndrome requests level 3 hospital with intensive care units for neonate and mother. The treatment of this syndrome requires termination of the pregnancy as soon a possible, either by cesarean section or by vaginal delivery if cervical conditions are optimal (without any maternal or fetal complications). Before 32 weeks, a more expectative attitude could be acceptable with the prematurity permitting corticotherapy for fetal pulmonary maturation. This corticotherapy can improve temporary biological parameters but there are no proven benefits to consider improvement for long term maternal or fetal prognosis. During the postpartum, evolution is usually spontaneously favorable. Recurrences are not frequent.