The results of two empirically designed and potentially non-cross-resistant combinations administered sequentially in advanced breast cancer with the intent of achieving a high rate of durable complete remissions were analyzed. The two drug combinations consisted of cyclophosphamide plus Adriamycin and high-dose methotrexate plus cisplatin given for a total of three cycles; twenty evaluable patients, not previously treated with chemotherapy, were entered into the study. Ten patients were allocated to receive cyclophosphamide and Adriamycin first followed by high-dose methotrexate and cisplatin, while the remaining patients received the opposite sequence. The overall response rate for the entire group was 85% (17 of 20). However, only three of 20 (15%) patients achieved complete remission. One additional complete response was observed when treatment was prolonged for an additional complete cycle. The overall median duration of response was 13 months (range, 5-20+ months). Responses were similarly distributed among different sites of lesions. Myelosuppression and gastrointestinal toxicity were mild and transient. Reversible acute renal failure was observed after methotrexate administration in three cases. Present results indicate that overall this sequential treatment appears effective in patients with advanced breast cancer. However, the lack of an increased complete remission rate over conventional regimens coupled with a potential risk of renal toxicity prevents further studies with this multiple drug combination.