An all‐metal feedthrough which permits superconducting leads to pass from the4He bath into the vacuum region of a cryostat is described. The all‐metal construction facilitates rapid assembly and enables the seal to withstand rapid temperature changes resulting from the precooling of the apparatus with liquid nitrogen. Use of the device is limited to those applications, such as operation of superconducting magnets, in which the presence of normal connections between the various leads or to the metallic structure of the cryostat can be tolerated.