It is vitally important to know accurately the ultrasonic energy levels of electronic equipment that generates and sends ultrasonic energy into the human body. Therefore, a radiation force measuring technique was developed to measure the ultrasonic energy generated by such equipment. Ultrasonic energy levels of less than 1 mW/cm2have been measured, with good repeatability. The equipment used is a Mettler Balance, model H‐20‐T, with a readable sensitivity of 0.01 mg and a target that detects the incident radiation force. The target is attached to the balance weighing pan and suspended in water under the balance by a nylon line. The balance has a built‐in tare, used to counteract the ultrasonic energy force that illuminates the target. In addition the tare is adjusted to counteract the surface tension that normally occurs at the nylon support line, which would interfere with the accuracy of power measurements. The target consists of an air‐backed reflector that has a half angle of 45°. This angle and the air space behind the thin metal surface makes the target a nearly perfect reflector. To make certain that no ultrasonic energy is reflected from the walls of the water tank, the ends of the tank are tilted about 20°, and all the inside surfaces are lined with ultrasonic energy absorbing material. This equipment has been in use now for over a year. Ultrasonic energy power measurements have been made on many different sizes, configurations, and frequencies of ultrasonic transducers. Details of this technique of measuring ultrasonic power will be reviewed in the paper.