Abstract Two cases of spinal subarachnoid haematoma occurring after spinal anaesthesia are reported. In the first case, lumbar puncture was attempted three times in a 81-year-old man ; spinal anaesthesia trial was than abandonned, and the patient given a general anaesthetic. He was given prophylactic calcium heparinate soon after surgery. On the fourth day, the patient became paraparetic. Radiculography revealed a blockage between T 10 and L 3. Laminectomy was performed to remove the haematoma, but the patient recovered motor activity only very partially. The second case was a 67-year-old man, in whom spinal anaesthesia was easily carried out. He was also given prophylactic calcium heparinate soon after surgery. On the fourth postoperative day, pulmonary embolism was suspected. Heparin treatment was then started. Twelve hours later, lumbar and bilateral buttock pain occurred, which later spread to the neck. On the eighth day, the patient had neck stiffness and two seizures. Emergency laminectomy was carried out, which revealed a subarachnoid haematoma spreading to a level higher than T 6 and below L 1, with no flow of cerebrospinal fluid, and a non pulsatile spinal cord. Surgery was stopped. The patient died on the following day. Both these cases are similar to those previously reported and point out the role played by anticoagulants. Because early diagnosis of spinal cord compression is difficult, the prognosis is poor, especially in case of paraplegia.