The use of children as haematopoietic stem cell donors represents an ethical dilemma. For some investigators, this is even more questionable if the children underwent peripheral blood progenitor cell (PBPC) collection. Due to these controversies, information related to adverse events (AE) in paediatric donors and variables related to the collection is scanty. We analysed 152 PBPC collections, and compared the complications and results between young children, older children and adults. The pattern of AE was shown to vary according to the age of the donor. Older paediatric donors and adults had a higher incidence of complaints related to PBPC priming (54.3% vs. 79.7%, respectively) than the youngest children (12%). On the other hand, these donors had a lower incidence of AE during PBPC collection (19.6% older children, 37.3% adults) mainly related to hypocalcaemia, than the youngest donors, who suffered mainly cardiovascular complications due to hypovolaemia (51.7%). The only variables related to collected cell dose were total blood volume processed per donor body weight, and CD34(+) cell count before apheresis. The donor/recipient body weight ratio predicted the outcome of collection in a single large volume leukapheresis. Donors with body weight ratio >or=0.75 had 4.69 times higher likelihood to reach the minimum target cell dose.