Cardiac tamponade is an unusual earliest presentation of undiagnosed metastatic adenocarcinoma of unknown origin. Malignant pericardial effusion requiring drainage is also a poor prognostic marker with reported median survival of 6.1 months. A choroidal mass may be the presenting sign of systemic malignancy; the diagnosis of metastatic ocular tumour is important as it portends poor prognosis. We are reporting an unusual presentation of an undiagnosed metastatic adenocarcinoma presenting in an elderly male primarily with loss of vision due to choroidal mass causing retinal detachment and repeated episodes of dyspnea due to recurrent pericardial effusion causing cardiac tamponade. Fluid analysis from pleura and breast biopsy revealed evidence of metastatic adenocarcinoma. Immunohistochemistry finding were suggestive of possible lung or gastrointestinal tract as a primary source. Imaging studies showed widely spread malignancy involving abdominal viscera, mediastinum, lung, pericardium, choroid and brain. He showed features of pericardial constriction on echocardiography after fluid drainage due to pericardial infiltration. He expired before he could have received palliative chemotherapy.