Fifteen patients suspected of having 18 intracardiac masses by two-dimensional echocardiography underwent MR imaging. In MR imaging, intracardiac masses were evaluated on both short TE (TE = 20-35 msec) and long TE (TE = 50-80 msec) spin echo sequences, and were differentiated from myocardium or papillary muscle. Three masses were excluded (they were papillary muscle) by MR imaging, and three were additionally found in patients with tuberous sclerosis. Fifteen masses were found by both echocardiography and MR imaging, one of which was stagnant blood. Cine MR imaging was needed to differentiate between thrombus and stagnant blood. MR imaging is useful for the evaluation of intracardiac masses. It is recommended in addition to echocardiography when cardiac tumors are suspected, especially in patients with tuberous sclerosis.