There is a high rate of cardiac involvement in malignant melanoma (MM), but such cardiac metastases are usually diagnosed late. This report describes four cases with different clinical presentations of MM cardiac involvement that were investigated by magnetic resonance imaging (MRI). The MM cardiac involvement was asymptomatic in one case, detected because of a superior vena cava syndrome in a second, and because a tamponade in the remaining two cases. MRI permitted the diagnosis of cardiac metastases of MM, which was not made by echocardiography in one case. By precisely detecting the extent of the tumors, MRI was a great help in management, especially when an isolated cardiac metastasis was suitable for surgical ablation (two cases). Because both clinical signs and transthoracic echocardiogram are not very sensitive for diagnosing MM myocardial involvement, MRI can help provide such a diagnosis and ensure better treatment-monitored decisions.