Treatment with 5-fluorouracil is common in oncological patients. Side effects on bone marrow, skin, and mucous membranes have been reported. Cardiotoxicity, which is less predictable, can be life-threatening. Manifestations include angina, arrhythmias, infarction, heart failure and cardiogenic shock. The toxic mechanisms that might be involved have been much discussed but have not yet been clearly established. Current evidence supports the possibility of a metabolic effect in common with the cascade secondary to ischemia due to coronary disease. Based on a case report, we discuss the usual clinical presentation, treatment and prognosis. Finally we make recommendations for managing patients being treated with 5-fluorouracil.