After lumbar puncture (LP) an epidural CSF leakage caused by delayed closure of a dural defect leads to a decrease in CSF pressure. The resultant venous dilatation as well as downward shift of the brain with traction on pain-sensitive blood vessels and nerves frequently evokes post-lumbar puncture headache (PLPH), when the patient assumes the upright position. In previous studies differing opinions have been expressed about the prophylactic value of the posture taken by the patient after LP. The present study was designed to evaluate the benefit of the decrease of hydrostatic CSF pressure on the dural rent, when the patient lies down in a prone position with the head tilted down at an angle of 10 degrees for 30 min immediately after LP: is it possible to accelerate the closure of the dural defect in this way and prevent PLPH? One group of patients (n = 78) lay in a prone position with the head tilted down at an angle of 10 degrees for 30 min, the other group (n = 82) rose immediately after LP. PLPH was found to be independent of the posture in both groups and affected 44% and 41% of the patients, respectively, so that there is no longer any justification for requiring patients to remain in bed after LP.