The purpose of this study was to investigate and evaluate the current technical performance of ultrasound imaging device displays in the Hospital District of South Ostrobothnia and in Pirkanmaa Hospital District. Ultrasound device monitors are used in diagnostics as the interpretation of the image is generally done simultaneously while the doctors perform the examination. There are certain recommendations about the technical performance of these kinds of diagnostic displays, but they are not generally applied to ultrasound devices. The performance of the displays was evaluated with tests and test patterns developed by a task group set by the American Association of Physicist in Medicine (AAPM). Only certain tests were chosen to be conducted as the protocol would otherwise become too heavy while the benefit from additional information would have been minimal. The focus of the study was on luminance measurements and the measurement of illuminance. The results show that the technical performance of most of the displays are not sufficient. The lifetime of the ultrasound machine surpasses the lifetime of the display, but nothing is currently done as there is no proper quality assurance protocol. The lack of proper quality assurance protocol is due to the fact that no legislation or regulations require it as non-ionizing radiation is used. This means that the quality of ultrasound imaging devices depends mainly on the physicists and maintenance engineers working in the hospitals. The singular most important technical performance parameter is the maximum luminance of the display. Although the luminance responses were evaluated against the Grayscale Standard Display Function (GSDF), it is questionable if GSDF compliance should be required from ultrasound device displays. Based on this research the measurement of the maximum luminance should be executed at least annually. The measurement procedure is easy, and it can be taught to any of the staff members and it can tell a lot about the condition of the display. It is also suggested that the hospitals should find out the cost of changing the display and thus probably prolonging the lifetime of the whole machine.