We investigated the differences in safety and management of adverse events of chemotherapy among three hospitals, Sakai Municipal Hospital, Takarazuka Municipal Hospital and National Hospital Organization Osaka-minami Medical Center. The main purpose of this study was to equalize the spread of breast cancer chemotherapy regimen. The following three regimens were evaluated; epirubicin (75 mg/m(2)) /cyclophosphamide (500 mg/m(2)) (EC75), epirubicin (75 mg/m(2)) /cyclophosphamide (500 mg/m(2)) /5-fluorouracil (500 mg/m(2)) (FEC75) and epirubicin (100 mg/m(2)) / cyclophosphamide (500 mg/m(2)) /5-fluorouracil (500 mg/m(2)) (FEC100). Sixty-three patients were evaluated. We studied the level of myelosuppression after each regimen. As a result, there was no significant difference in neutrocyte counts at nadir after chemotherapy among hospitals and regimens. However, the values tended to be ranked EC75>FEC75>FEC100. In addition, we examined the risk of febrile neutropenia (FN) according to the multi- national association for supportive care in cancer (MASCC) scoring system. Almost all patients (61/63) were in the low risk group of FN, and only two patients had developed FN. At one hospital, patients receiving chemotherapy were prescribed ciprofloxacin tablets prophylactically for prexia over 38 deg C, and the patients learned from it. Thus, no marked difference in the safety (side effects such as myelosuppression) was recognized. However, management of side effects was different among these hospitals. In conclusion, it is very important to provide patients with adequate information on side effects.