The lumbar spine pedicle screw guide has a base for covering at least one exposed spinous process of the lumbar vertebra and a sliding top disposed over the base and configured for movement over the length of the base along a first axis. At least one calibration arm having a straight portion and a curved portion is movably connected to the sliding top and configured for movement along a second axis perpendicular to the first axis. A pedicle access unit is mounted on each calibration arm and is capable of being secured at different locations thereon. The sliding top can be adjusted to align the calibration arms with a selected vertebra so that medical instruments and a screw can be accurately guided through the pedicle access unit into a pedicle of the selected vertebra.
