We present a case demonstrating the utility of cardiovascular magnetic resonance (CMR) in the diagnosis of a cardiac mass. A 70-year-old female who presented with chest pressure and left sided jaw pain was found to have a cardiac mass on transthoracic and transesophageal echocardiography that was diagnosed as an atrial myxoma. A cardiac magnetic resonance test determined the mass to be more consistent with a thrombus than a myxoma through a stepwise approach using multiple pulse sequences. Thus, unwarranted and potentially risky thoracic surgery was avoided by the incorporation of a systematic evaluation by cardiac MRI.