An adjustable awl for forming a hole for the insertion of a screw or other device in a pedicle or other body part. The awl comprises an elongated housing having an open end, and an elongated awl member movably mounted in the housing and being extendable beyond the open end to vary the length of the awl. The awl comprises means for locking the awl member in a selected position relative to the housing. The awl member is provided with markings thereon to indicate its position relative to the housing.