In Europe and the United States, beginning steroid treatment on the day before docetaxel(DTX)administration is recommended to reduce edema and/or hypersensitivity symptoms. In this study, we investigated the usefulness of starting steroid treatment on the day before DTX administration. Patients with breast cancer who received 4 or more cycles of DTX with or without trastuzumab or DTX and cyclophosphamide(TC)with or without trastuzumab as pre- or post-operative chemotherapy in our hospital between January 2010 and May 2012 were analyzed in this retrospective study. Patients were classified as those who started taking steroids on the day of DTX administration(GroupA: 62 patients)and those who started taking steroids on the day before DTX administration(GroupB: 47 patients). The incidence of edema and/or hypersensitivity was retrospectively compared between these groups after the completion of 4 cycles of chemotherapy. The incidence of edema was significantly lower in GroupB (n=12, 25.5%)than in GroupA (n=28, 45.2%; p=0.04). The onset of edema also tended to be later in GroupB. The incidence of hypersensitivity tended to be lower in GroupB(n=3, 6.4%)than in GroupA (n=8, 12.9%), although this difference was not statistically significant. These results suggest the benefit of steroid treatment started on the day before DTX administration in preventing the development of edema. Results also suggest that the onset of edema could be delayed by this administration method. We recommend that steroid premedication, which can lead to a reduction in adverse drug reactions to DTX, be used to help maintain patients' quality of life(QOL)and to support treatment continuation.