Objective This study aimed to evaluate the biomechanical characteristics of the anterior upper thoracic plate fixation system (AUTP). Methods Twelve specimens were divided into 2 groups: the AUTP group and the anterior cervical locking plate (ACLP) group. Bone mineral density was assessed in all specimens. The specimens were loaded with pure bending moments of ±4 Nm to move toward extension/flexion, right/left lateral tilt, and right/left axial rotation. Each specimen was tested in 3 load cycles under 3 conditions (native, destabilized, and torsion). The tightening moments were assessed in every screw using a torsion meter. Results The tightening moment of the AUTP screws was more pronounced than the ACLP (P < 0.05). Significant decreases after stabilization with the AUTP compared with the native situation were observed in the AUTP group (P < 0.05). In terms of the direction of lateral tilt and torsion, the neutral zone increased significantly after stabilization with the AUTP compared with the native situation (P < 0.05). Conclusions The AUTP was shown to provide more rigidity to the destabilized spine than the ACLP. [ABSTRACT FROM AUTHOR]