A description is given of an ultrasound imaging system which permits visualization of two-dimensional cardiac anatomy in real time. This system relies on phased array principles rather than mechanical means to rapidly steer the ultrasound beam through the cardiac structures under investigation. The system uses a linear array of 16 ultrasound transducers which are resonant at approximately 2 MHz. At the site of contact, the array currently in use measures 24 by 14 mm where the latter dimension corresponds to the elevation dimension of each of the 16 active elements. Performance characteristics of this imaging system are given.