The Oncopaz Cooperative Group designed a chemotherapy regimen to modulate UFT (Tegafur and Uracil) with leucovorin. The regimen consisted of a high intravenous dose of leucovorin, followed by oral UFT and oral leucovorin twice daily for 14 days. Based on the promising results obtained with this regimen in patients with advanced colorectal cancer, the Oncopaz group performed several phase II trials using this combination with other drugs to treat advanced gastric, lung, head and neck, and breast cancers. When combined with etoposide in gastric cancer, the regimen was shown to be active and well tolerated. However, when used with cisplatin to treat non-small cell lung cancer, a low response rate and high toxicity precluded its recommendation for further study. The addition of carboplatin in the treatment of head and neck cancer demonstrated moderate activity with low toxicity. In an ongoing trial of advanced breast cancer, preliminary results indicate that the combination of idarubicin, UFT, and leucovorin is active, with moderate, primarily hematologic toxicity. Trials of new combinations are warranted to take advantage of the pharmacokinetic properties and oral bioavailability of UFT and leucovorin.