Cardiotoxicity of 5-fluorouracil and cisplatin chemotherapy for esophageal, head and neck and gastric carcinoma was studied. Before treatment all patients had a cardiac evaluation and during treatment serial electrocardiographic (ECG) recordings were performed. In the pre-treatment evaluation signs of cardiovascular disease were found in 31(38.75%) patients. During treatment cardiotoxicity was observed in 12(15%) patients. The incidence of cardiotoxicity was not higher in patients with signs of cardiovascular disease than in those without in the pre-treatment evaluation. The most common signs of cardiotoxicity were chest pain, ST-T wave changes and arrhythmia. This study suggests that patients on 5-fluorouracil and cisplatin treatment should be under close supervision and that the treatment should be discontinued if chest pain and/or arrhythmias are observed.