Abstract: A method for analyzing the radiation sensitivity of an integrated circuit to determine the components, particularly tansistors, of greatest radiation sensitivity, including the application of a narrow radiation beam to portions of the circuit, as by applying the beam of a scanning electron microscope, so the radiation is applied to only one transistor at a time. The circuit is operated under normal bias conditions during the application of radiation in a dosage that is likely to cause malfunction of at least some transistors, while the circuit is monitored for failure of the irradiated transistor. If the irradiated transistor does not fail, then the other transistors are irradiated one at a time. When a radiation sensitive transistor is found, then the radiation beam is further narrowed and, using a fresh integrated circuit, a very narrow beam is applied to different parts of the transistor such as its junctions to locate the points of greatest sensitivity.