5-fluorouracil (5FU) is a largely employed antimetabolite, responsible for several well-known toxicities like hand-foot syndrome, diarrhoea, mucositis or leucopenia. Cardiotoxicity of 5-FU is known but uncommon and usually not life-threatening. The incidence has varied from 1.5 and 18%. The physiopathology is controversial, although more recent data suggest a myocardial toxicity. Clinical presentation include chest-pain, cardiac arrythmia, myocardial infarction or global cardiac failure. Electrocardiographic features are usually aspecific, with ischemic signs. The main treatment is to stop the 5-FU infusion and to introduce symptomatic cardiologic treatment. Although the prognosis is good, the mortality ranges between 2.2 and 13% in case of symptomatic cardiotoxicity. Secondary prophylaxis remains controversial.