Ultrasound activated resorbable pin osteosynthesis (UARPO) has recently shown favourable results in operations on children suffering for craniosynostosis. However, data on complications coming with this new technique in children suffering from craniosynostoses are scarce and have only been assessed retrospectively so far. It has been the aim of the present study to prospectively follow up children undergoing craniosynostosis surgery with a focus on complications related to UARPO materials. Ten pediatric patients (3 female/7 male) were operated due to craniosynostosis at an average age of 9.1±3.8 months using UARPO (SonicWeld/Resorb-X, KLS Martin, Tuttlingen, Germany). Clinical followup evaluations were carried out 1, 3, 6, 9, 12 and 18 months after surgery according to signs of local infection, stability of the remodeled cranial vault and the palpability of the osteosynthesis material. If secondary surgery was necessary, the indication was documented and evaluated by histological and wound smear examinations. No intra-operative or postoperative complications during the inpatient period occurred. 3 patients needed secondary operation due to a localized chronic swelling at the former incision site which developed 3, 9 and 12 months after the operation. Histological examinations yielded a giant cell formation surrounding the resorbable materials in all cases. Additionally, the wound smear showed a bacterial infection in one site. The current prospective study is the first in the field. It reveals a high percentage of delayed foreign body reactions with UARPO, bearing the need of secondary surgery. It seems that this high complication rate found in the present prospective study may weigh out the advantages of UARPO.