Oncologic emergencies are clinical situations that can lead to death in a short time (24-48 hours) if not quickly faced. In the clinical practice of the medical oncologist, such situations do not infrequently occur. The onset of oncologic emergencies may depend on the presence of cancer itself, the therapies carried out to counteract cancer, or the patient’s predisposition to develop such events. Mediastinal syndrome, spinal cord compression, endocranial hypertension, pancytopenia, metabolic syndromes, deep vein thrombosis, pulmonary thromboembolism, disseminated intravascular coagulation and the massive pericardial effusion are the main medical emergencies in oncology occurring in clinical practice. It is essential to recognize the aforementioned situations early in order to treat them promptly, thus avoiding serious consequences. This paper is aimed at presenting an overview on the topic, offering practical suggestions useful in daily clinical practice.