Intracardiac echocardiography (ICE), an echocardiographic examination from within the heart itself, has been proposed as a new modality for cardiac imaging. A major shortcoming has been the limited depth of field provided by previously available devices. We used 10 MHz catheters for ICE to determine if this lower frequency would allow for greater display of cardiac anatomy. We performed ICE in seven animals; myocardial ischemia was induced in three. With the imaging catheter in the right atrium, all four cardiac chambers and valves could be imaged. Advancing the transducer into the right ventricle allowed for short-axis images of the left ventricle. Coronary perfusion territories and segmental wall motion abnormalities could be observed. We then performed ICE in six patients by advancing the catheter into the right side of the heart percutaneously. Structures of the right side of the heart, the mitral valve, aortic valve, left atrium, and portions of the left ventricle, were visualized. Congenital and acquired abnormalities could be identified. There were no complications. We conclude that ICE with 10F, 10 MHz ultrasound catheters allows for expanded imaging capabilities because of the increased depth of field. With this imaging modality, congenital and acquired abnormalities as well as myocardial ischemia can be detected.