Objective: To report three cases of cardiotoxicity related to the admi
nistration of 5-fluorouracil (5-FU) in patients with cancer. Clinical
features: Three patients with gastrointestinal malignancies were being
treated with combined radiotherapy and chemotherapy regimens. Two pat
ients developed myocardial ischaemia and the other a ventricular arrhy
thmia in association with 5-FU administration. Intervention and outcom
e: All patients survived the cardiac event. No patient was rechallenge
d with 5-FU. Radiotherapy was continued, achieving a good tumour respo
nse. Conclusion: Cardiotoxicity is rarely reported with 5-FU. The card
iac events can be life threatening. It is difficult to predict which p
atients will be affected. Clinicians need to be aware of this potentia
l toxicity and monitor patients appropriately.