From February 1987 to December 1988, 34 patients with histologically confirmed advanced colorectal carcinoma were entered in a phase II trial with 5-fluorouracil (5-FU) and folinic acid, for evaluation of treatment effectiveness and toxicity. Our data confirmed that the association 5-FU and folates represents an effective and moderately tolerated palliative treatment, with diarrhea being the only dose-limiting toxicity.