Background: Leukaemia is a malignant neoplasm characterized by clonal proliferation of white blood cells within the bone marrow. Despite an increase in the white blood cell count, the leukaemic leukocytes are non-functional. The oral complications arising in leukaemic patients can be attributed to the direct and indirect effects of immunosuppressive chemotherapy. Methods: This case report describes severe maxillary and mandibular necrotizing stomatitis and osteomyelitis in a young female patient after chemotherapy for acute leukaemia. On physical examination, the patient presented malnourished with pale skin, cervical lymphadenitis, frequent fever and generalized pain. The intra-oral clinical examination found halitosis, multiple ulcers, necrotizing stomatitis and osteomyelitis located in the maxillary and mandibular regions. The necrotizing stomatitis and osteomyelitis were treated locally with atraumatic removal of the necrotized tissues. The patient received a daily preventive protocol consisting of oral hygiene care, including twice daily brushing, and mouthrinses with a solution of chlorhexidine. She was also treated with systemic metronidazole and amoxicillin for 21 days. Results: During the course of management the patient's oral condition improved with some re-epithelialization being noted. However, severe alveolar bone destruction remained evident. Thirty-two months after presentation of the initial symptoms, the patient died due to complications related to leukaemia recurrence (haemorrhage, sepsis and respiratory distress syndrome). Conclusions: Dental monitoring during cancer treatment is imperative in order to emphasize the importance of dental plaque control and the maintenance of a healthy periodontal condition throughout medical treatment.543262265