A two-dimensional ultrasound imaging system capable of producing high resolution, cross-sectional images of the heart in real-time has been developed. This system relies upon phased-array principles to rapidly steer and focus the ultrasound beam through the cardiac structures under investigation. A hand-held, linear array of 24 transducers is manipulated on the anterior chest wall to image various cardiac structures. Images of high line density are presented in selectable sector arcs to a maximum of 90 degrees. This imaging system has proved particularly useful for the detection of a variety of left ventricular and cardiac valvular disease.