A ball dropping assembly is shown of the type which is connected in a string of pipe for dropping a ball in the pipe string. A main body is mounted on the pipe. The main body has an interior bore which communicates with the interior of the pipe. A cam housing is received within the main body bore and has a ball receiving recess formed in the interior thereof. A ball dropping can is rotatably received within the cam housing. The can has partially cut-away sidewalls which form a camming surface for the ball. A retaining nut engages and seals the cam housing and can within the body whereby rotation of the can with respect to the cam housing houses the camming surface to contact the ball to thereby eject the ball from the ball receiving recess into the interior of the pipe without opening the assembly to the atmosphere.