Cardiac tamponade may be the first or predominant symptom of some pathologies but its etiology is not uncommonly unknown on admission to hospital. The purpose of this study was to evaluate the predominant causes of cardiac tamponade in previously healthy patients treated emergently in a single cardiac surgical center. The study involved 81 patients with the mean age of 58.1±16.0 years who underwent emergent subxyphoid pericardiotomy due to cardiac tamponade. Pericardial effusion was analyzed macro- and microscopically. Examinations done in the cardiac surgical department revealed pericarditis secondary to infection (n=17) or autoimmunologic processes (n=2) and malignancy in 18 patients (predominantly of the lungs (n=11)). Pericardial effusion obtained from patients with viral and autoimmunologic-induced pericarditis was straw-color and odorless while with bacterial infections dark yellow, iridescent and usually malodorous. Additional workup in the regional hospitals enabled to reveal malignant tumors in 29 patients, leukemia or lymphoma in 5 subjects. In all but one of the neoplastic cases, pericardial fluid was turbid and dark red or plummy. In 10 patients etiology of tamponade remained unknown. In conclusion, cardiac tamponade in previously healthy patients may be occasionally the predominant symptom of cancer, especially of the lungs. Macroscopic intraoperative appearance of pericardial fluid may be helpful in identification of causative condition of cardiac tamponade.