Chemotherapy-induced nausea and vomiting (CINV) are highly distressing symptoms for cancer patients undergoing cytotoxic chemotherapy. This dataset was obtained from a homogenous group of Chinese breast cancer patients who were uniformly planned to receive a highly emetogenic (neo)adjuvant chemotherapy regimen, consisting of doxorubicin and cyclophosphamide (commonly known as AC). Patients were being randomized to one of the two antiemetic regimens: aprepitant, ondansetron and dexamethasone with (the Olanzapine arm) or without olanzapine (the Standard arm). Patients underwent self-reported diaries and questionnaires to record their nausea and vomiting symptoms, use of rescue medication as well as their quality of life (QOL). The primary and secondary endpoints have focused on efficacy analysis during the first cycle of AC chemotherapy; the results have been reported in The Breast 1. In this Data in Brief article, we provide outcome of the analysis of data collected during multiple cycles of chemotherapy. The data reported here include the proportion of patients with “Complete Response”, “Complete Protection” and “Total Control” of emesis in the acute (0–24 h), delayed (24–120 h) and overall periods (0–120 h), as well as QOL data during all the 4 cycles of AC.