Adjuvant chemotherapy has a real but modest impact on the disease-free and overall survival of patients with breast cancer. Recent attempts to improve its effectiveness have focused on dose intensity and new agents. Sequential therapy maximized dose intensity while limiting overlapping toxicity. Sequential therapy using doxorubicin followed by cyclophosphamide/methotrexate/5-fluorouracil (CMF) has been found superior in patients with high-risk resectable breast cancer. The novel chemotherapy agent paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is now known to be highly active in advanced breast cancer and appears to be clinically non-cross-resistant with doxorubicin. Therefore, this drug is being studied as a component of the next generation of adjuvant chemotherapy regimens. The most appropriate way to incorporate paclitaxel has not yet been defined, but its concurrent administration with other agents has, in some cases, been troublesome. Based on the demonstrated advantage of the sequential plan for doxorubicin and CMF, we conducted a series of pilot trials testing sequential high-dose therapy. Initially, we studied multiple cycles of doxorubicin followed by cyclophosphamide; we later added paclitaxel to this regimen. These phase II studies demonstrate the feasibility of sequential therapy with doxorubicin, paclitaxel, and cyclophosphamide, and early disease-free survival results are promising. Cooperative group projects are under way or planned to further define the activity of these regimens.