Leukaemia, a form of abnormal and atypical proliferation of undeveloped white cells, is the most common form of malignant neoplasia in childhood. The different forms of leukaemia are characterized by a high incidence of oral complications. Moreover, oral injuries may be the first predictor of the illness helping to diagnose leukaemia, even if the histologic examination of the marrow is required for a certain diagnosis. Actually the early diagnosis of oral injuries is really important for prevention and treatment of the complications that may arise during the therapy: a better prognosis and lower morbidity and mortality for this illness ensue. Furthermore, even after remission, the young patient increasingly needs a constant monitoring of the oral cavity because of the delayed effects of the illness and the therapy. Therefore a dental treatment programme for paediatric haemato-oncological patients is very important to improve quality of life of leukemic children.