Background: In adults, the definition of rare tumor refers to those who have less than six cases per 100,000 inhabitants. When this definition is applied to the infantojuvenil population, all diagnoses would be considered rare. The definition of rare tumor in the infantojuvenil population is not consensual, being generally based on proposals from different groups of experts, which, for the most part, classify them as those with incidence of less than two cases per million or included in certain groups of classification of carcinomes. Objective: To analyze the definitions for rare tumors in children and adolescents proposed in the literature. Methods: Scope review answering the question "what does the literature define as a rare tumor for children and adolescents?". Review carried out in the databases: Medical Literature Analysis and Retrievel System Online (MEDLINE) via PubMed, Embase and Latin American and Caribbean Literature in Health Sciences (LILACS), with the descriptors: "childhood cancer", "rare tumors" and "incidence". Results: 236 records were identified in the databases. After the removal of duplicates, 230 studies were submitted to the reading of titles and/or abstracts, of which 216 were excluded because they did not meet the eligibility criteria. Thus, 14 articles were read in full, resulting in 14 studies included in the review. The definition of rare tumor varied among the articles studied. The European group JARC defines rare tumors as VRT (very rare tumors), this list is composed of those who have less than 2 cases per million. Another European group, EXPeRT, defines as those with an incidence of less than 2 cases per million and/or with no dedicated clinical trials/studies for the pediatric population, in line with the Italian group TREP that defines VRT in children and adolescents as those who have incidence of less than 2 cases per million in patients not included in protocols. The Children’s Oncology Group defines as rare those listed in subgroup XI of the International Classification of Childhood Cancer (ICCC), this list covers carcinomas and other malignant epithelial neoplasms, including melanomas. Thus, many studies converge on the definition that rare tumors in pediatrics are those that are often diagnosed in the adult population but have low incidence in children and adolescents, with an incidence equal to or less than 2 cases per million5-9. These diagnoses are mostly of epithelial origin and do not have a treatment protocol for the age group from 0 to 19 years, mainly due to difficulties in conducting clinical trials due to the small and sparse number of cases. Conclusions: The definitions of rare tumors in children and adolescents vary in the literature, but they converge on <2 cases per million and are not included in therapeutic protocols. It is important to draw up an official list of rare tumors in the child and adolescent population, so that, based on a standardized definition, countries and international consortia can conduct comparable studies and advance prevention strategies, considering the incidence patterns specific to each country, and in improving the treatment of these tumors.