Chemotherapy given by continuous infusion may have different toxicity profiles and efficacy than when given by bolus administration. Thirty-one patients with refractory tumors entered a phase I trial in which paclitaxel was administered for 7 days by continuous infusion every 28 days. Only one patient required hospitalization for treatment, because of an initial poor performance status, and most carried out normal activities on an ambulatory basis. After the first three patients, patients were entered in cohorts of five with the starting dose of 120 mg/m2. Each subsequent cohort was begun at a dose 10% higher than the previous cohort. Later courses within each cohort were increased 10% in an individual patient, if toxicity allowed. Nausea was rare. Of 15 patients with a soft tissue sarcoma refractory to doxorubicin, dacarbazine, ifosfamide, and etoposide, there were: one partial response (PR), five stable diseases and eight progressive; one patient was not evaluable for response. The PR occurred in a patient with a very aggressive sarcoma and very bulky disease, and was maintained for more than 1 year. We conclude that paclitaxel given by ambulatory continuous i.v. infusion is well tolerated with a maximally tolerated starting dose of 160 mg/m2.