Our policy has been to administer granulocyte colony-stimulating factors (G-CSF) for the mobilization of peripheral blood stem cells (PBSC) on an outpatient basis. We evaluated the safety of G-CSF-administered PBSC donation in outpatients and inpatients. Subjects : PBSC donations from 86 healthy donors (78 related, 8 unrelated) between January 2011 and December 2019 were included; 74 donors were administered G-CSF as outpatients, and 12 while under hospitalization. Evaluation of the length of hospital stay (LOHS) : LOHS of the donors who were administered G-CSF as outpatients (median, 2 days; range, 1 to 4 days) was significantly shorter than that of the inpatient donors (median, 4.5; range, 4 to 5) (P<0.0001). Adverse events of G-CSF administration : There was no significant difference in the incidence of adverse events related to G-CSF administration between the donors who were administered G-CSF as outpatients and those as inpatients (P=0.1786). Efficacy of PBSC mobilization : Most donors donated sufficient PBSC (median CD34+×106 cells/kg recipient body weight, 5.65). There was no significant difference in the number of collected CD34+ cells between the two groups (P=0.6671). Conclusion : Outpatient-based administration of G-CSF for PBSC mobilization was feasible without compromising donor safety or PBSC donation efficacy.