We report a case of secondary heart involvement in AIDS-related primary lymphoma of the liver. A worsening dyspnea led to the diagnosis of pericardial effusion, and transesophageal echocardiography revealed the presence of large endocardial ventricular masses. Clinical suspicion of a lymphomatous origin was confirmed at the autopsy, which showed an extranodal dissemination pattern (heart, liver, intestine, and lung). In AIDS patients, both primary and secondary lymphomatous heart involvement are increasing in incidence. Clinical symptoms and signs are vague. Since the hematogenous route is the most common pattern of involvement, even extrathoracic lymphomas can present heart dissemination. Thus, it should be suspected in lymphoma patients who present with even mild aspecific heart symptoms. Appropriate imaging procedures include transesophageal echocardiography and, if possible, ECG-gated MRI. A negative transthoracic echocardiograph does not exclude the presence of myocardial tumor. Chemotherapy is only occasionally beneficial, and the prognosis remains poor.