Abstract: A heat dissipation cassette to be installed in the battery chamber of a notebook PC for cooling down the interior operational temperature of the notebook PC is disclosed. The heat dissipation cassette includes a cassette body that defines an air supply channel and an air exhaust channel. The air supply channel and the air exhaust channel are aligned with an air supply opening and an air exhaust opening defined in the endwall of the notebook PC, when the heat dissipation cassette is installed in the battery chamber. A supply fan is mounted in the air supply channel to supply cool air into the notebook PC through the air supply channel and the air supply opening. An exhaust fan is arranged in the air exhaust channel to exhaust hot air out of the notebook PC through the air exhaust opening and the air exhaust channel.