The paper opens with some information regarding conditions governing fatal injury due to electric shock.Then follows a discussion of the electrical characteristics of the low-voltage circuits found in X-ray plant, and of the problems of earthing and safety in respect of supply potentials.Reference is made to the presence of high-frequency currents in the primary circuit, and some suggestions are offered for the removal of their effects.Some advantages and disadvantages of signal lights are mentioned.The paper next deals with the secondary side of the X-ray equipment, and reviews the various voltages and typical circuits employed. A brief study is made of the possible shock effects due to three types of plant.Safety measures are then considered in some detail. Arrangements for partial and total enclosure of dangerous components of X-ray equipment are examined, and instances are cited from commercial and experimental apparatus.Examples of the use of high-voltage flexible cables in X-ray work are mentioned, and some characteristics of the cables are discussed. Particulars are given of methods of “making off” high-voltage cable ends.Finally, some foreign safety regulations are reviewed; while in the Appendix an extract on the subject of electrical safety is quoted from the International Recommendations for X-ray and Radium Protection.