We report a iatrogenic case of retroperitoneal haematoma consecutive to an emergency femoral venous catheterization. The indication of the catheterisation was a hemorrhagic shock after a dilapidating traumatism of leg in an obese patient in whom peripheric venous access was impossible and vascular filling urgent. In spite of the existence of an initial reassuring blood backward flow, a retroperitoneal haematoma had been constituted gradually and explained an absence of haemodynamic improvement in spite of the surgical haemostasis and an adapted intravascular filling. The CT scan showed an iatrogenic lesion of the right iliac vein and justified the immediate infusion stop. The femoral catheter was withdrawn at the 48th hour and the patient discharged at the 6th day.