An x-ray tube cooling system including a heat sink at least partially disposed within an evacuated housing of the x-ray tube and having a cooling block partially received within the bearing housing so as to absorb heat transmitted to the bearing assembly and bearing housing. Extended surfaces, are disposed in a coolant chamber cooperatively defined by the cooling block and a shell within which the cooling block is partially received. The shell defines a coolant chamber entrance and coolant chamber exit in fluid communication with the coolant chamber. The coolant chamber entrance and exit communicate with corresponding coolant inlet and outlet passageways, respectively, cooperatively defined by a pair of insulators which retain the heat sink in a predetermined orientation within an evacuated envelope of an x-ray device. A circulating coolant contacts the extended surfaces and thereby removes heat from various structures of the x-ray device.