We have investigated prospectively the incidence of bacterial contamination of 114 spinal and 20 epidural needles collected immediately after lumbar puncture of the subarachnoid or epidural space. Bacteriological examination revealed bacterial contamination of 24 (17.9%) of the needles, mainly coagulase-negative staphylococci (21; 15.7%) followed by yeasts (2; 1.5%), enterococcus (1; 0.8%), pneumococcus (1; 0.8%) and micrococcus (1; 0.8%). Our results suggest that even during aseptic puncture for lumbar anaesthesia, there is a significant rate of needle contamination.