Background. Substantial evidence supports the use of adjuvant trastuzumab with chemotherapy for patients with human epidermal growth factor receptor (HER)-2 ؉ breast cancer; however, a lesser amount of data is available to guide use of this therapy in older patients and in those with significant medical comorbidities. The goal of the current study was to understand how patient age and health status impact oncologists' decisions to recommend adjuvant therapy in older women with HER-2 ؉ breast cancer.Methods. Medical oncologists (n ؍ 151) participated in an online survey regarding treatment recommendations for a hypothetical patient of varying age and health status with tumor stage 2, nodal stage 2, estrogen receptor-negative, HER-2 ؉ breast cancer. Survey respondents recommended either chemotherapy plus trastuzumab, chemotherapy alone, trastuzumab alone, or no therapy. The effect of age and health