For studying microbubbles in a medical ultrasound field (ultrasound frequency between 0.5 and 5 MHz) ultra high-speed imaging camera is required. The ultrasound typically lasts 3 - 20 cycles during which the response of the microbubbles can be highly non-linear. The frame rate of such a high-speed camera therefore should exceed 10 million frames per second (Mfps). The number of frames should be sufficient to record the whole process, therefore, more than 100 frames are desirable. In this manuscript we describe a digital ultra high-speed camera system which combines the superior flexibility and sensitivity of CCD detectors with the high number of frames available in rotating mirror cameras. In a standard run the "BRANDARIS 128" camera records a full sequence of 128 digital images at a frame rate of 25 Mfps.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.