Primary malignant tumors of the heart are rare; the biggest group is sarcomas. Cardiac metastases make up the biggest group of secondary cardiac tumors. We present a rare case of cardiac metastasis (3.1 × 3.2 × 2.8 cm) localized in the right atrium, originating from a large cell neuroendocrine lung carcinoma, with close contact to the tricuspid valve and inferior cava vein.