In pregnant women, Thrombotic Thrombocytopenic Purpura (TTP) mimics severe preeclampsia because of the overlapping of these symptoms. We report the case of a 28-years-old woman who presented severe thrombocytopenia (platelets at 34 G/L) at 31 gestational weeks. The day after, she showed anaemia, worsening thrombocytopenia (platelets at 6 G/L) and an isolated increase of AST (91 UI/L). Plasmapheresis was performed without improvement. Secondary, she presented hypertension and proteinuria at 15 g/24 hours and elevated liver enzymes (AST 116 UI/L). A cesarean section was performed on day four for suspected HELLP syndrome. We observed in postpartum a progressive increase of platelets and regression of hepatic cytolysis. The sFlt1/PlGF ratio was elevated at 855, the results of ADAMTS13 activity were below 5 %, and the ADAMTS13 gene was mutated. TTP and HELLP syndrome can co-exist and can complicate one another. TTP lead to placental malperfusion. Further studies are needed to confirm the diagnosis value of the sFlt-1/PlGF ratio in TTP pregnant women.