PBSCs have become the preferred source of autologous stem cells for supporting high-dose chemotherapy in childhood solid tumors. The aims of this retrospective study were to examine the optimal timing for administration of G-CSF after chemotherapy and to identify the patients from whom an optimal dose of PBSCs can be harvested. We evaluated the timing of G-CSF administration for harvesting PBSCs in patients with childhood solid tumors. G-CSF was administered immediately after chemotherapy in eight patients (11 harvests, long-term group) and following recovery from hematological nadirs in 17 patients (21 harvests, short-term group). The median duration of G-CSF administration was 22 vs. 5 days, respectively (p < 0.005), and the dose of harvested CD34(+) cells (×10(6) /kg) was 1.4 vs. 2.9, respectively (p = 0.023). Our results suggest that short-term G-CSF administration is a good strategy for harvesting PBSCs in these patients.