OBJECTIVE. The purpose of this article is to describe the characteristic cardiac MRI features of primary and secondary cardiac tumors, including differentiation from masslike lesions, such as thrombus or focal myocardial hypertrophy. CONCLUSION. The frequency and type of cardiac tumors in children differ from those in adults. Although transthoracic echocardiography is the initial imaging technique of choice for evaluation of cardiac tumors, cardiac MRI is an important complementary modality for characterization of the mass and effect on cardiac function.