PURPOSE: Little is known about how oncologists’ adopt new treatments for breast cancer. This study investigated influences on oncologists’ adoption of paclitaxel as adjuvant chemotherapy for early-stage breast cancer, 9 months after presentation of phase III data suggesting improved disease-free and overall survival when paclitaxel was added to doxorubicin and cyclophosphamide for such patients. METHODS: Self-reported data were collected with a mail survey of a random sample of 1,200 oncologists practicing in the United States. Using Rogers’ model, we measured four types of influences on adoption of innovation: (1) communication channels, (2) innovation characteristics, (3) a practitioner’s social system, and (4) physician characteristics. Multiple regression analysis assessed the associations between oncologist adoption of paclitaxel for early-stage breast cancer patients and variables representing the modeled influences on adoption. RESULTS: On average, respondents (n = 181) reported having adopted paclitaxel for 37% of their early-stage breast cancer patients. The overall model was significant, with seven variables associated (P ≤ .05) with adoption of paclitaxel. Significant influences on adoption included use of symposia as a therapy information source, physician experience with paclitaxel to treat late-stage breast cancer, and perceived advantage in efficacy of paclitaxel. CONCLUSION: As new modalities become available to treat cancer, it is vital to understand what factors influence oncologists and patients when choosing to use them. Those parties interested in fostering the adoption of new breast cancer treatments should address features of communication channels (eg, use of symposia), characteristics of new treatments (eg, perceived advantage in efficacy), physicians’ social systems (eg, patient requests), and characteristics of potential adopters (eg, previous experience with the treatment).