The invention relates to a motor vehicle seat comprising a back rest (11), a height-adjustable head rest (12), and an aeration device (13) that is integrated into the back rest and comprises a blow opening (16) arranged in the upper side (111) of the back rest (11) and used to blow out hot air. The aim of the invention is to improve the aeration device by reducing the aeration noises and generating a comfortable warm feeling for the user of the seat, in the head, neck and shoulder region. To this end, a diffuser (19) is arranged in the intermediate space between the back rest (11) and the head padding (15) of the head rest (12), said diffuser being embodied and oriented in relation to the blow opening in such a way that the hot air flow through the blow opening towards the head padding is deflected into a wide, diffuse hot air flow flowing around the head, neck and shoulder area of a user (10). The length of the diffuser (19) can be varied and the diffuser itself is fixed to the lower side (151) of the head padding (15) and to the upper side (11) of the back rest (11), so that it is involved in the height adjustment of the head rest.