A 9F combination intracardiac imaging and electrophysiology mapping catheter has been developed and tested to help guide diagnostic and therapeutic intracardiac electrophysiology procedures. A 7.5 MHz, 64 element, side looking phased array was used for sector scanning from the tip of the catheter. Multiple electrophysiology (EP) mapping sensors were mounted as ring electrodes just proximal to the array for electrocardiographic synchronization of ultrasound images. The catheter has been used in vivo in a porcine animal model and has demonstrated useful intracardiac echocardiographic (ICE) visualization of both cardiac tissue and electrophysiology catheters in the right atrium. The catheter performed well in high frame rate imaging, color flow imaging, and strain rate imaging of atrial and ventricular structures.