Malignant pericardial effusion is a common and serious manifestation in malignancies. The origins of the malignant process include solid tumors or hematological malignancies, while primary neoplasms of the pericardium are less common. In the oncological patient, pericardial effusion may develop by several different mechanisms, namely by direct or metastatic spread of the primary process or as a complication of antineoplastic therapies. In some cases, pericardial effusion may be the first manifestation of the disease, and that is why malignancy must be excluded in every case of an acute pericardial disease with cardiac tamponade at presentation, rapidly increasing pericardial effusion and an incessant or recurrent course. Thus, the definite differentiation of malignant pericardial effusion and rapid diagnosis are of particular therapeutic and prognostic importance. Management of these patients is multidisciplinary and requires team work, but at present there is a need for further research. An individual treatment plan should be established, taking into account cancer stage, the patient's prognosis, local availability and experience. In emergency cases with cardiac tamponade or significant effusion, initial relief can be obtained with pericardiocentesis. Despite the magnitude of this serious problem, little progress has been made in the treatment of pericardial effusion secondary to malignant disease.