The diagnosis of a rare case of giant intraventricular fibroma in an infant by MRI in comparison with other imaging modalities, such as echocardiography and angiography, is discussed. For preoperative planning only MRI showed the myocardial infiltration. The myocardial blood supply of the tumor could be evaluated qualitatively by contrast-enhanced MRI, but the direct visualization of the distally located branches could only be assessed by coronary angiography. Magnetic resonance coronary angiography using the navigator technique failed to depict the distal part of the coronaries. The obstruction of the left ventricle outflow tract could be assessed and quantified by all imaging modalities.