Abstract: A chain tensioning device includes a pair of spaced blocks having opposed surfaces configured for abutment with a chain. An elongated connecting bar extends between the blocks and through aligned apertures formed through each of the blocks. The blocks are independently adjustably secured along the length of the connecting bar by set screws. The opposed chain abutment surfaces are configured as mirror image rectangular channel tracks having a central projection. In use, the device is placed in engagement with an endless loop type sprocket driven chain and the blocks are adjustably positioned along the length of the connecting bar with the rectangular channel tracks in engagement with opposite sides of the endless chain loop. The device provides a simple and inexpensive mechanism for tensioning a chain in the absence of a supporting structure for mounting an additional idler sprocket.