The ultrasonic properties of microbubble contrast agents need to be fully understood if reproducible images and quantitative results are to be produced. Additional aspects of the physical and chemical environment into which the contrast agents are introduced also need to be taken into account, and their effect-on contrast agent performance evaluated. A setup that provides an accurate and reproducible data-acquisition system is presented and evaluated in this paper. The linear range of this system is assessed, as well as its accuracy and precision. A new approach to the investigation of contrast agents, based on normalised backscatter, is discussed. Also, a common technique of degassing, widely used in other areas, is described and evaluated to determine its appropriateness to contrast agent studies. (C) 2000 World Federation for Ultrasound in Medicine & Biology.