We describe a man who was diagnosed with non-small cell lung cancer following previous treatment for small cell lung cancer. He developed dyspnoea, paroxysmal nocturnal dyspnoea and orthopnoea. Trans-thoracic echocardiogram revealed a large mass within the right atrium. The patient proceeded to thoracotomy at which time unresectable metastatic tumour was found in the right atrium infiltrating into the pericardium. Metastatic involvement of the heart by tumour is rare and is found at autopsy in 1-3% of unselected cases in various series. This translates into a finding of cardiac metastases in approximately 10% of autopsies where malignancy is diagnosed. Most cases are clinically silent and are undiagnosed in vivo. Echocardiography, CT and MRI are complementary investigations, and are all used in the evaluation of cardiac lesions. When metastatic disease is in question, MR and CT imaging offer advantages over echocardiography, chiefly a wider imaging field which allows evaluation of distant disease.