The objective of this study was to assess the efficacy of an injection of 100 microg/kg of pegfilgrastim in haematopoietic recovery and mobilization in children following 32 courses of chemotherapy. End points were duration of neutropaenia, myeloid recovery and PBMC collection. Neutropaenia lasted a mean of 4.7 days (+/-2.13 days). Myeloid recovery occurred at a median of 10 days (inter quartile range (IQR) 8-11). Febrile neutropaenia complicated 13 courses (40.6%). Mobilization was observed in 20 out of 26 assessable courses (76.9%). The rise in CD34+ cells occurred at a median of 6 days (IQR 4-7) after PEG and remained >20 per microl for 6 days (IQR 4-8), with a median value of 80 per microl (IQR 48-170.5). The median CD34+ cell peak was 165 per microl (IQR 82.5-331), 9 days (range 6-14) after PEG. PBMC were collected on average at day +5 (+4 to +9) after PEG. In 93.3% of collections, at least 3 x 10(6) per kg CD34+ cells were collected through a single apheresis. Myeloid recovery occurred in all cases within 15 days, without concomitant thrombocytopaenia. The incidence of primary febrile episodes is in line with data in the literature and with our own historical experience. A long-lasting period of circulating CD34+ cells allowed for more accurate scheduling of apheresis.