We evaluated the efficacy and safety of the RV21-01 scalp cooling device in controlling hair loss during chemotherapy in this study. Thirty-nine breast cancer patients who underwent anthracycline- and/or taxane-based chemotherapy were assigned to the scalp cooling group(27 patients)and the hair loss observation group(12 patients). The alopecia rate using the NCI alopecia toxicity criteria and the quantitative alopecia toxicity grade was 51.9%(14/27 patients)and 100%(12/12 patients)in the scalp cooling and hair loss observation groups, respectively. Regarding safety, all subjects in both the scalp cooling and hair loss observation groups experienced adverse events; only 1 subject in each group experienced a severe adverse event due to chemotherapy and majority of the subjects in both groups experienced minor adverse events. RV21-01 scalp cooling therapy was demonstrated to be effective in reducing hair loss in patients undergoing standard chemotherapy for breast cancer. In addition, the adverse events associated with the scalp cooling therapy were minor and mild, and hence, deemed acceptable.