Fifty-two patients received one of two doxorubicin (DOX)-based admixtures; DOX plus cyclophosphamide (CTX) or DOX plus vinblastine (VBL) administered as a continuous 24-hour infusion for protracted periods. Compatibility and stability of the two-drug admixture was established for a minimum of 7 days. Twenty patients on the DOX/CTX admixture were infused for a median of 20 days (range, 7-56 days). DOX/VLB was infused in 32 patients for a median of 18 days (range, 5-48 days). Dose limiting toxicity was leukopenia observed in 14/52 patients; 4/20 on DOX/CTX and 10/32 on DOX/VLB. Additional toxicities observed included stomatitis (15%) and subclavian vein thrombosis (23%). Tumor responses were observed in 11 patients, including 6/13 breast cancer; 2/2 hepatoma; 2/4 sarcoma and 1/1 ovarian cancer. Responses were relatively short-lived and no responses were noted in known anthracycline resistant tumors. Admixtures of chemotherapeutic agents represents a novel, but feasible, mechanism for delivery of multiple drugs with an infusion schedule and can be considered for Phase III comparative clinical trials.