Objective The aim in this study was to evaluate the efficacy of the ball tip probe technique in placing pedicle screws in patients.Methods From May 2009 to June 2010,we used ball tip probe technique in pedicle screw placement in patients with scoliosis,spondylolisthesis,spinal fractures and other diseases.The ball tip probe consisted of a metal shaft with a metal ball-shaped tip whose size included 1.5,2.5,3.0,3.5 mm in diameter.The ball tip probe with a diameter of 1.5mm owned a high rigidity and certain flexibility.Ball tip probe technique:A high speed bur was used to remove cortical bone and create a starting point,and then the ball tip probes is tapped gently by a hammer for making a guide hole through the pedicle into the vertebral body.The accuracy of the pedicle screw placements was evaluated on postoperative axial CT scanning The pedicle screw placements was compared between the the ball tip probe group and conventional freehand technique group.Results Three hundred and twelve screws were evaluated in the ball tip group and 276 in the conventional freehand group.All the screws (100％) were in the desired pedicle in the ball tip group and 215 (78％) in the conventional group.In the conventional group,23 screws (8.3％) were classified as medial violation; 38 (13.7％) as lateral violation.A significant difference was determined between the 2 groups regarding the pedicle breaches.No vascular,pulmonary,or neurological injuries caused by pedicle screws placement was found in either group.Conclusion This study demonstrates the accuracy and reliability of the ball tip probe technique in pedicle screw placement.This technique can probably reduce the risk of complications of screw misplacements.