A wood chipper to be lifted, transported and powered by a tractor having a power take-off at its rear, has forward and rearward housings. A chipping unit, located in the forward housing, is mounted on a driven shaft extending into the rearward housing and there provided with a pulley connected by a belt to a pulley on a drive shaft rotatably supported at one end by the rearward housing. The drive shaft extends below the first housing and is connectable to the power take-off of the tractor. The chipping unit has a forward square load-carrying member to which a circular, rearward blade carrying member is connected through impellers by which chips cut by blades are discharged.