Cardiac myxoma of the right atrium was diagnosed in a 64-year-old woman by use of MRI. With the MRI technique, an absence of signal intensity was shown within parts of the tumor, indicating the presence of intratumoral calcification. The MRI also demonstrated an intratumoral area of high signal intensity which was related to the presence of hemorrhage within the tumor. Both MRI findings were confirmed on pathologic examination of the surgical specimen. Magnetic resonance imaging may be a useful test to evaluate the heart for mass lesions in those patients in whom echocardiography is inadequate.