The invention relates to a medical diagnostic X-rayapparatus (1) comprising an X-raysource (13), a hollow carrier (5) to which the X-raysource is connected, and a cooling mechanism (3) provided with a cooling means to cool the X-raysource (13) during use of the X-rayapparatus (1). The cooling means is in direct thermal contact with the carrier (5), thus providing an efficient cooling mechanism (3) for the X-raysource (13).