Abstract: A power hammer for driving piles and the like which includes a housing having a ram carried therein for reciprocating vertical movement to strike, during its downward movement, an anvil slidably carried within the lower portion of the housing. The portion of the housing in which the anvil is carried is formed with an annular recess, and the anvil includes an annular flange projecting into the recess to form an enclosed chamber beneath such flange. Air pressure generated by the ascendency of the ram is transmitted to the enclosed chamber to impose an upwardly directed force on the anvil whereby the weight of the anvil is utilized to oppose the upwardly directed force imposed on the power hammer during the ascending movement of the ram.