Eighteen patients with measurable advanced colorectal cancer and four with metastatic gastric cancer were treated with cisplatin 100 mg/m2 day 1 and 5-fluorouracil (5-FU) 1000 mg/m2 administered over 6 h i.v. infusion from days 2 to 5 every 21 to 28 days. Five out of 15 fully evaluable patients with colorectal cancer experienced a partial response (33%) while amongst the three evaluable patients with gastric cancer one complete and one partial remission were achieved. Both hematological and non-hematological side-effects were mild. Our preliminary results seem quite interesting and deserve further evaluation.