A crossbow sighter is used to align the sight used on a crossbow to the axis of the groove on the crossbow. In this manner, the cross bow bolt will strike close to, or at, the location sighted by the sight. The crossbow sighter fits into the groove and has a body with a length that extends past the bow string when the bow string is in its fully relaxed position. The bow string rests against the body and applies cross-axial pressure to the crossbow sighter and helps retain it in the groove while aligning the crossbow sight.