In a multicentre Phase III trial, 182 patients were randomized to either folinic acid (FA) (200 mg/sqm i.v. x 5 days) + 5-fluorouracil (5-FU) (400 mg/sqm i.v. in 15' x 5 days) every 4 weeks (Arm A), or to 5-FU alone at the same dosage (Arm B). Response rates were 20.6% (Arm A) and 10% (Arm B) with a significant (p = 0.046) advantage for FA + 5-FU. Median time to progression (6 and 6 months) and overall survival (11.5 and 11 months) were similar in the 2 groups of patients, while neither treatment was effective in reducing pain or improving performance status. Univariate analysis showed that no prognostic factors other than treatment influenced response, although survival was affected by the number and site of metastases, performance status, and the presence and degree of pain. Toxicity was acceptable and lower in comparison with other Phase II-III trials, with no significant difference between the 2 arms. However, in individual patients, grade 3-4 side effects (mainly stomatitis and diarrhoea) were observed, particularly in patients receiving FA: this led to interruption of the treatment in 7 cases. The superiority, in terms of objective response, of FA + 5-FU over 5-FU alone would seem to justify a large-scale evaluation of this combination in the adjuvant setting. Further improvements in relation to advanced disease (i.e., modifications to the schedule and/or introduction of other modulators) are warranted.