Abstract: A saw chain sharpener for sharpening the left hand and right hand cutting teeth and the rakers of a saw chain while the chain is mounted in situ on a saw bar. The apparatus includes a base, a saw bar clamp mounted on the base for clamping a saw bar in a substantially vertical position. A grinding assembly including an electric motor and a grinding wheel is mounted respectively on first or second grinding assembly mounting posts. The mounting posts are secured on opposite sides of the saw bar clamp. The apparatus also includes an indexing device mounted on the bar clamp and which is spaced from the grinding surface of the grinding wheel when the grinding wheel is pivoted into the grinding position for selective supporting engagement with the rear edges of the saw chain cutting links. The saw chain can therefore move forwardly but not rearwardly when the indexing tooth is in position. The indexing device is adjustable to determine the lengths to which the cutting teeth are to be ground.