Seventy-seven patients with previously untreated, measurable, histologically confirmed, metastatic adenocarcinoma of the rectum or sigmoid were randomized to receive either epirubicin 90 mg/m2 (75 mg/m2 if prior radiotherapy) i.v. once every 3 weeks or 5-fluorouracil 500 mg/m2 (450 mg/m2 if prior radiotherapy) i.v. once daily for 5 consecutive days every 4 weeks. None of 38 (0%) evaluable patients who received epirubicin demonstrated a response, whereas seven of 39 (18%) patients who received 5-fluorouracil had an objective response. Epirubicin is ineffective against metastatic rectal cancer at the dose and schedule used.