This phase 2, multicenter, open-label trial investigated the safety and tolerability of tbo-filgrastim in pediatric patients receiving myelosuppressive chemotherapy. In total, 50 patients 1 month to below 16 years of age with solid tumors without bone marrow involvement were stratified into 3 age groups (2 infants, 30 children, 18 adolescents) and prophylactically administered tbo-filgrastim 5 µg/kg body weight once daily subcutaneously. The administration started after the last chemotherapy treatment in week 1 of the first cycle and continued until the expected neutrophil nadir had passed, and the neutrophil count had recovered to 2.0×10/L. The primary endpoint was safety and tolerability of tbo-filgrastim; secondary endpoints included efficacy. The mean (SD) number of doses administered was 9.2 (2.83) in children and 7.3 (1.88) in adolescents. Serious treatment-emergent adverse events were reported in 24% of patients; the most common were febrile neutropenia (FN) (12%), anemia (8%), and thrombocytopenia (8%). Nine patients (18%) experienced mild treatment-related treatment-emergent adverse events; the most common were musculoskeletal and connective tissue disorders (8%). No deaths or withdrawals occurred. The incidence of severe neutropenia (SN) was 52% and the mean (SD) duration of SN was 1.8 (2.21) days; FN incidence was 26%. A daily dose of tbo-filgrastim 5 μg/kg body weight administered to pediatric patients demonstrated a safety profile consistent with the safety profile in adult patients. The incidence of FN was on the lower end of the range reported in the literature and the SN results provide supportive data on the efficacy of tbo-filgrastim in pediatric patients.