Background: Neoadjuvant chemotherapy is commonly performed to reduce the size of tumors before partial mastectomy to improve the rate of breast-conservation. Few studies have been conducted to assess the neoadjuvant chemotherapy experience of women diagnosed with breast cancer and their responses to it. Purpose: To explore the experience of women diagnosed with breast cancer who received neoadjuvant chemotherapy and their responses to it. Methods: The grounded theory was adopted as the methodology. Participants were recruited using purposive sampling. The data were collected using semi-structured, in-depth interviews and analyzed using open, axial, and selective coding. Results: A total of 15 women newly diagnosed with breast cancer participated in this study, with information showing that the core category oscillated between the sizes of the tumor. The three categories included difficulty in coping with the physical response to chemotherapy, absence of role fulfillment, and uneasy emotions. The coping strategies used by the participants included: body and mind adjustment, hiding, family labor adjustment, and changing the pace of social life. Conclusions/Implications for Practice: The participants experienced tremendous physical and psychological stress during their neoadjuvant chemotherapy, in which tumor response assessment served as a critical time point. Medical professionals, in addition to noting changes in women’s physiological response, must pay attention to their psychological burden and provide emotional support and treatment information as needed.