This is a phase I dose-escalation study of uracil and tegafur (in a molar ratio of 4:1 [UFT]) administered in combination with calcium folinate and paclitaxel in metastatic breast cancer. This trial was initiated to 1) determine the maximum tolerated dose and dose-limiting toxicities of UFT plus calcium folinate (Orzel) administered three times per day for 21 days in combination with paclitaxel; and 2) define the appropriate dose for phase II testing. Thus far, 14 patients have been accrued to three dose levels. Two patients developed dose-limiting toxicities at dose level 3. One patient experienced grade 3 hypotension. A second patient experienced grade 3 vomiting, grade 4 diarrhea, and severe hand-foot syndrome. Two partial responses and one complete response have been observed. Early trends suggest that this regimen is active in metastatic breast cancer and is well tolerated. Completion of this study is anticipated in 1999.