We present a patient with sickle cell trait who suffered avascular necrosis of the maxilla as a complication of maxillary osteotomy. Understanding the blood supply of the maxilla and how possible patient related, anaesthetic and operative factors affect it, is important in understanding how the vascularity of the maxilla can become compromised in a surgical procedure. The perioperative parameters were analysed to identify any prognostic elements. Avascular necrosis of the maxilla is a rare complication of orthognathic surgery with few cases reported in the literature. There are identifiable risk factors that can influence the blood supply of the maxilla. Careful preoperative assessment is required to exclude patient factors that have the potential to affect tissue vascularity. This in conjunction with sound anaesthetic and surgical technique should all minimize the risk of avascular necrosis. Even so it is still possible for this rare complication to occur.