Osteonecrosis (ON), a significant complication following treatment of acute lymphoblastic leukemia (ALL), has a profound impact on quality of life of ALL survivors. We studied incidence and outcome of ON in patients treated on or according to Australian and New Zealand Children's Haematology/ Oncology Group (ANZCHOG) study 8 at The Children's Hospital at Westmead. The study involved retrospective chart review of the patients. ON was defined by development of symptoms and confirmed by magnetic resonance imaging. From 2002-2011, 251 patients (143M, 108F, 59 Standard Risk (SR), 159 Medium Risk (MR) 5 High Risk (HR), and 28 Very high risk (VHR)) were treated according to study 8. Eighteen (7M, 11F, 2 SR, 12 MR, 4 VHR) patients developed ON (7.2%). Median age at diagnosis was 13.05 years(4.3-16.7). Incidence of ON in patients > 10 years at diagnosis was 29%. Six out of 18 patients developed ON after allogeneic stem cell transplantation. Median time from diagnosis to the development of ON following chemotherapy for ALL was 1.15 years (range 0.25-2.12). Most patients were treated with intravenous Zoledronic acid. At last follow-up, three patients had undergone arthroplasty, two patients were symptom free, and the remaining 13 patients reported persistent pain with activity. A majority of patients with ON of the hips had radiological progression. Overall, 7% of patients with ALL developed ON. Age >10 years was the most important risk factor. At last follow-up, 70% of patients had persistent symptoms. Although Zoledronic acid improved pain, most patients with ON of the hips had radiological progression.