A heat dissipation assembly includes a heat sink, a retention module and a clip for securing the heat sink to the retention module. The heat sink includes a base for contacting with a heat generating device. The retention module includes a bottom wall and a first sidewall defining a slot therein and extending from the bottom wall. The clip includes a connecting portion pivotably connected to the retention module. The heat sink rests on the bottom wall of the retention module with an end thereof fitting in the slot, and an opposite end thereof being pressed by the clip. The clip can be in a released position that the clip is pivotable, so that the heat sink is removable from the retention module, and a locked position that the clip presses the heat sink. Thus, the heat sink can be secured to the heat generating device expediently.