A heat dissipation assembly includes a printed circuit board, first and second heat dissipation units each defining a channel therein and a heat pipe. The printed circuit board has an electronic heat-generating component mounted thereon. The first heat dissipation unit is attached to a top surface of the heat-generating component. The second heat dissipation unit has a main portion disposed beneath the printed circuit board and another portion extending from a level beneath the printed circuit board to another level above the printed circuit board. The heat pipe is wholly disposed above the printed circuit board and comprises an evaporating portion rotatably received in the channel of the first heat dissipation unit and a condensing portion rotatably received in the channel of the second heat dissipation unit.