PURPOSE: To investigate the impact of the COVID-19 outbreak on the attitudes and practice of Italian oncologists toward breast cancer care and related research activities. METHODS: A 29-question anonymous online survey was sent by e-mail to members of the Italian Association of Medical Oncology and the Italian Breast Cancer Study Group on April 3, 2020. Only medical oncologists (both those in training and specialists) were invited to complete the questionnaire. RESULTS: Out of 165 responding oncologists, 121 (73.3.%) worked in breast units. In the (neo)adjuvant setting, compared with before the emergency, fewer oncologists adopted weekly paclitaxel (68.5% v 93.9%) and a dose-dense schedule for anthracycline-based chemotherapy (43% v 58.8%) during the COVID-19 outbreak. In the metastatic setting, compared with before the emergency, fewer oncologists adopted first-line weekly paclitaxel for HER2-positive disease (41.8% v 53.9%) or CDK4/6 inhibitors for luminal tumors with less-aggressive characteristics (55.8% v 80.0%) during the COVID-19 outbreak. A significant change was also observed in delaying the timing for monitoring therapy with CDK4/6 inhibitors, assessing treatment response with imaging tests, and flushing central venous devices. Clinical research and scientific activities were reduced in 80.3% and 80.1% of respondents previously implicated in these activities, respectively. CONCLUSION: Medical oncologists face many challenges in providing cancer care during the COVID-19 outbreak. Although most of the changes in their attitudes and practice were reasonable responses to the current health care emergency without expected major negative impact on patient outcomes, some potentially alarming signals of undertreatment were observed.