Purpose: The unintentional and unrecognized cannulation of an extradural vein is a potentially serious complication of an epidural anesthetic. The present study was undertaken to assess the incidence of blood vessel puncture related to epidural catheterization performed in three different body positions. Methods: The study was conducted in 900 (three groups of 300) obstetric patients undergoing continuous epidural analgesia during ther labour and who were randomly allocated to three groups. Epidural catheterization was performed with patients in the sitting, lateral recumbent horizontal, or lateral recumbent head-down position. Results: There was a lower incidence of vessel cannulation when this procedure was performed in the lateral recumbent head-down position (2%) than in the lateral recumbent horizontal (6%) and in the sitting position (10.7%). Conclusion: Adoption of the lateral recumbent head-down position for the performance of lumbar epidural blockade, in labour at term, reduces the incidence of lumber epidural venous puncture.