Background Bisphosphonate use in adult patients has been linked to osteonecrosis of the jaw (ONJ). This complication has not been systematically assessed in a paediatric population receiving bisphosphonates. Objective To assess our cohort of paediatric patients treated with intravenous bisphosphonate for occurrence of ONJ. Design Observational study at a tertiary children's hospital. Patients A total of 42 paediatric patients with osteoporosis who received bisphosphonate infusions for a mean of 6.5 years (SD 2.7 years) were assessed clinically and radiographically for possible ONJ. Among 42, 37 patients had received disodium pamidronate 1 mg/kg/dose at a mean cumulative dose of 19.8 mg/kg and zoledronic acid (ZA) 0.05 mg/kg/dose at a mean cumulative dose of 0.49 mg/kg; four had received ZA and one received pamidronate alone. Invasive dental treatment during bisphosphonate treatment, a known risk factor for osteonecrosis, was specifically assessed. Results In all patients assessed, including 11 who had invasive dental treatment, there were no cases of osteonecrosis. Conclusion ONJ has so far not been demonstrated in this patient group.