Recently, various electrical equipment and radio equipment (for example, mobile cellular telecommunication system, private mobile radio, personal handy-phone system, etd.) are being used in a wide range. Therefore, radio interference due to disturbance waves radiated from such equipment are now public concerns in general. The problem of these radio interference is discussed internationally, and many international standards on the measuring methods and limits have been established for the strength of radiated disturbance waves. Electric traction systems will potentially radiate disturbance waves, because they are using high electric power. So the electric traction systems also can cause radio interference. The radio interference from electric traction systems is discussed by International Special Committee on Radio Interference (CISPR), and a draft of CISPR Publication (standardized document) that contains international standard guideline of Electromagnetic Compatibility (EMC) on electric traction systems is being draw up. This paper outlines the discussions on radio interference from electric traction systems by CISPR and introduces international trends into future.