Despite the increase in survival rates, childhood cancers are among the leading causes of death. Oral and systemic infections are one of the most important problems in the management of cancer patients treated with intensive treatment protocols. The most important and common source of sepsis in patients with cancer is the mouth. Microorganisms can contribute to the development of systemic infections. The absence of a normal barrier facilitates sepsis in cases such as mucositis. Oral infections during treatment can be seen in 40-90% of patients. Risk factors associated with infection are neutropenia/ neutrophil dysfunction, impairment in lymphopenia/lymphocyte functions, mucositis, dry mouth, malnutrition, poor oral hygiene, type of cancer, stage, and treatment protocol, history of previous oral/non-oral infections, history of previous pulpal and periodontal disease, pericoronitis, and endodontic treatment. Patients diagnosed with cancer should be seen by the dentist before treatment, and if there is enough time before treatment, dental filling, extraction, and periodontal care and treatment should be planned. However, because tumors with a high growth rate are observed in children, a faster approach is required in diagnosis and treatment. Often, there is not enough time. As a result, oral infections are an important cause of morbidity and mortality in children with cancer. Oral and dental examination should be evaluated before treatment in children diagnosed with cancer. During treatment, they should also be part of the routine examination. Patients and their families should be given regular training in this regard. Culture and/or biopsies should be performed from suspicious lesions and appropriate treatment should be initiated without delay.