A chain saw sharpening guide manually held in position on the saw chain comprising a support plate (11) carrying grooved rollers (13, 13a) mounted on brackets (12, 12a) depending from the plate (11). The rollers (13, 13a) are grooved (15, 15a) to receive the saw sharpening file (34) in rolling contact and maintain it parallel to the plate. In use the guide is located on the saw chain with the rollers straddling the chain with the file in contact with the saw tooth and with the rollers. A slot (16) in the plate (11) allows the operator to view the sharpening action. Variations provide graduations and stops for correct angle of cut and undercut of cutting edge plus adjustment of the saw tooth depth gauge.