During the summer of 1977, the Radiation Protection Bureau conducted a survey of ultrasound therapy devices in the Ottawa area. Data were accumulated on the use and performance of the equipment. Device parameters measured were the ultrasound frequency and output power, and timer accuracy. Operators were questioned on the number of patients treated per weak, treatments times, ultrasound intensity settings and the type of transducer-skin coupling agent used. Wide variations were found between the output power measured from the transducer and that indicated on the unit. It was clear from the survey that most devices were not delivering the ultrasound doses prescribed for the patients. The results of this and other surveys are being used by the Radiation Protection Bureau to determine the need for regulations which specify design, construction and performance standards under the Radiation Emitting Devices Act. The way in which survey results are used to draft performance standards is discussed, and important specifications that should form part of a device performance standard are included with rationales.