Oral complications are a significant cause of morbidity and potential mortality for children undergoing hematopoietic cell transplant (HCT). Oral complications can occur at all stages of HCT and can interfere significantly with transplant recovery. Mucosal disease caused by conditioning regimen toxicity and infection are frequent clinical problems. Untreated dental caries and periodontal disease may result in severe infections of the mouth and/or life-threatening systemic spread of the microbial pathogens. In the course of chronic graft-versus-host disease (GVHD), which can complicate HCT, lichenoid and ulcerative lesions of the mucosa are observed. Furthermore, total-body irradiation utilized in the conditioning regimens can cause early xerostomia and consequent dental decay and also result in significant dental and skeletal developmental anomalies. The dental health care team should have a key role in the support of HCT patients. The team's primary responsibilities are those related to the prevention of severe infections originating in the mouth, which includes providing instruction on oral prophylaxis and hygiene as well as direct intervention. Prevention and/or diagnosis and management of oral complications of HCT by the dental team can improve the success of a transplant by reducing morbidity, improving the quality of life, and reducing the cost of care. The authors present specific protocols for the diagnosis and prevention and for the management of oral complications in pediatric HCT.