PURPOSE: To clarify particularly how febrile neutropenia-related hospitalization (FNH) affects patients' daily lives, by analyzing real-world data on FNH among patients with early breast cancer (EBC) receiving perioperative chemotherapy in Japan. METHODS: This retrospective nationwide large-scale database study was conducted using anonymized claims data from 2010 to 2020. The patients with EBC who had available surgical records were included. Men, those aged < 18 years, and those who had not available chemotherapy records were excluded. FNH was defined as hospitalization during perioperative chemotherapy for EBC, with administration of intravenous antibacterial drugs and a diagnosis of FN, sepsis, infection, or fever. RESULTS: The analysis population included 33,310 EBC patients with a mean age of 56.9 years, who received a total of 267,535 perioperative chemotherapy cycles. FNH occurred in 1,910 patients (5.73%) and 2144 chemotherapy cycles (0.80%). Median duration of FNH was 6.0 days. Fourth-generation cephalosporins were the most used intravenous antibacterial drugs (50.42%). Median duration of intravenous antibacterial drugs administration was 4.0 days. Therapeutic granulocyte-colony stimulating factor (G-CSF) was used in 1285 patients (67.28%). Median cost for FNH was estimated to be 189 thousand yen in 1,474 chemotherapy cycles with FNH, in which patients received intravenous antibacterial drugs administration for 3-8 days. CONCLUSION: This nationwide real-world data analysis revealed the incidence, duration, treatment patterns, and medical cost of FNH in patients with EBC receiving perioperative chemotherapy in Japan. These findings indicate that FNH imposes a considerable burden on patients' daily lives, including time and financial impacts, contributing to the implementation of appropriate shared decision-making for primary G-CSF prophylaxis.