More than 50% of pediatric malignancies are leukemias or lymphomas. Oral changes associated with these conditions include: gingival oozing, petechiae, hematomas, ulcerations, gingival pain, gingival hypertrophy, mucosal pallor, pharyngitis, and lymphadenopathy. Current medical management for patients with hematologic malignancies includes chemotherapy, radiation, surgery, bone marrow transplantation or a combination of these modalities. Nearly 60% of patients diagnosed today with malignancy will be long-term survivors. Patients undergoing orthodontic treatment when a diagnosis of malignancy is made are best served by expedient removal of orthodontic appliances and delivery of retainers. After a patient has completed all cancer therapy and has at least a 2-year event-free survival, orthodontic treatment can be restarted.