The radiation stability of x‐ray membranes is of major importance for future development of x‐ray lithography and x‐ray microscopy. The primary concern in this respect is loss of dimensional stability due to the radiation damage. The dose required to introduce sensible distortion of the pattern on a membrane is far below that necessary for the radiolysis of the membrane material. The ability of a material to resist generation and accumulation of the radiation defects is related to its band structure. Mechanisms of radiation defect generation, protective mechanisms, and possible ways to control the radiation resistance are discussed.