The current study was designed to evaluate the feasibility and clinical utility of real-time 3-dimensional echocardiography (RT3DE) for detection of intracardiac thrombi with comparison to 2-dimensional echocardiography (2DE). The study included 45 consecutive patients with intracardiac thrombi detected by routine 2DE (mean age 45 ± 8.4 years, 75% males). The relevant features of the thrombus by 2DE and RT3DE (site, shape, and number) were assessed according to a subjective four-point score index for image quality (1 = not visualized, 2 = inadequate, 3 = sufficient and 4 = excellent). Measurements included: maximum diameter and volume. 2DE and RT3DE detected 45 thrombi (34 in the left ventricle, six in the left atrium, four in the left atrial appendage, four in the right atrium, and two in the right ventricle). RT3DE could detect seven additional thrombi in five patients (three in the left atrial appendage and four in the left ventricular apex). Visualization score by 2DE and RT3DE was comparable (Kappa index: 7.2). RT3DE measurements of maximum diameter were well correlated with 2DE (R ² = 0.88, P < 0.01) and showed better interobserver agreement than 2DE (2.88, −1.92 vs. 5.33, −3.87, respectively). RT3DE was superior to 2DE for assessment of thrombus mobility, differentiation between the thrombus and myocardium, and delineation of the changes in thrombi structure, e.g. calcification, degeneration, or lysis. In addition, volume calculation could be obtained by RT3DE only. In conclusion: RT3DE is comparable to 2DE for the assessment of the intracardiac thrombi and provided more detailed information beyond the scope of the established 2DE.