Anesthesiologists rely on his or her hand-feeling and experience to insertthe epidural needle into the epidural space when conducting epidural anesthesia.With no direct guiding and reporting on the distance between the epiduralneedle and the epidural space, this practice is fully depending onanesthesiologist's experience. Hence, it is a challenge for the less experiencedanesthesiologist to properly insert the epidural needle into the epiduralspace. In this study, we have developed a high frequency needle ultrasoundtransducer to assist the epidural space access. By inserting the high frequencyneedle ultrasound transducer into the hollow chamber of the epidural needle, thedistance between the tip of the epidural needle, ligament flavum, and duramater can be measured in real time by monitoring the reflected ultrasound signalin A-mode display. We have successfully applied the needle ultrasoundtransducer to assist in vivo epidural space insertion in a porcine model.