Abstract Calibrated, radiation-sensitive metal-oxide-silicon field-effect transistors (RADFETs) have been launched into space and used in the laboratory to measure the doses from a variety of radiation sources. These experiments have demonstrated that the RADFET provides a convenient method for the continuous monitoring of total dose. The electrical output consists of a d.c. voltage which can be converted electronically to a value for accumulated dose. The voltage can be read remotely and displayed continuously. This review briefly outlines the physical mechanisms by which radiation dose is registered by RADFETs, describes the characteristics and performance of a practical RADFET and discusses applications. In addition to the name “RADFET”, these devices have been called “MOS Dosimeters”, “Mosimeters” and “Space Charge (SC) Transducers”.