Numerous modalities have been used to diagnose and characterize noncompaction of ventricular myocardium (NCVM) including magnetic resonance imaging, two-dimensional echocardiography (2DE), contrast-enhanced 2DE, and angiography. The current case series examines the use of real-time three-dimensional transthoracic echocardiography (RT-3DE) in four such cases of NCVM. From December 2003 to March 2004, we performed RT-3DE using a Philips Sonos 7500 echocardiographic scanner equipped with a 2-4 MHz 3D matrix array transthoracic probe, to evaluate four patients with NCVM. The real-time 3D transthoracic probe allows for dataset acquisition in an ultrasound wedge, which can be manipulated instantaneously. In addition, complete 3D volume rendering is acquired, allowing for volumetric imaging. The age range of the patients was 2 months to 42 years. One patient had the codiagnoses of coarctation of the aorta and bicuspid aortic valve. In all four patients, RT-3DE enabled diagnosis and provided detailed characterization of the affected myocardium. Entire trabecular projections and intertrabecular recesses were easily visualized simultaneously, and endocardial borders were clearly demarcated. Wall motion abnormalities of the affected myocardium were clearly visualized. The compacted and noncompacted portions of the myocardium could be differentiated well. Our study provides preliminary data highlighting the utility and feasibility of RT-3DE in the clinical characterization of NCVM. The complex 3D nature of this disorder and the endocardial hypertrabeculation were more readily visualized than with 2DE.