Background: Childhood cancer, although considered rare (2% of global cases), is one of the main causes of death from disease in children and adolescents in Brazil and the world¹ ². Rare tumors, defined as those with an incidence of less than 2 cases per million³ ? ? present challenges such as late diagnosis, lack of standardized protocols and scarcity of epidemiological data. Despite international initiatives, such as the CureAll program of the World Health Organization?, there are gaps in knowledge about mortality due to these tumors in Brazil. Objective: to analyze the time trend of incidence of rare tumors in children and adolescents living in Goiânia, a capital city of the Central-West region of Brazil, between 2000 and 2020. Method: This is an ecological study of time series based on data from the population of children and adolescents (0-19 years) living in the city of Goiânia from 2000 to 2020. The capital of Goiás, a Brazilian state located in the Midwest region of the country, has about 1.5 million inhabitants, of which 353,000 are in the age group (0-19 years). Data from the Goiânia Population Cancer Registry and incidence calculation were used. Descriptive analysis, with subsequent analysis of time series using the Prais-Winstein linear regression method with robust variance. were used the population data by age available in TABNET/DATASUS. The data analysis was performed in the software R version 4.5.1. Results: In the period studied, 269 cases of rare tumors were recorded in the population aged 0-19 years. In total, 44 types of rare tumors were identified. Of these, 164 (61%) were female and 105 (39%) male. An increasing and significant trend was observed between 2000 and, with a Percentage Annual Variation (VPA) of 4.63% (95% CI: 2.38 - 6.93; p < 0.001). The analysis by age groups showed stationary trends in most of the groups, except for an increase between 1-4 years (VPA 17.55%) and a decrease between 15-19 years (VPA -4.19%). In the most frequent tumors showed stationary trends. Skin carcinomas and malignant melanoma were the most frequent. , an important highlight since the State of Goiás has one of the villages with the highest incidence of xeroderma pigmentosa in the world (Araras-GO), a disease that increases the chance of skin tumors by 10.000x³. Conclusion: Rare tumors in children and adolescents living in Goiânia present a pattern of incidence, associated with an increasing trend. The importance of investments in training and prevention of skin cancer in children and adolescents in the region is highlighted, since this was the most frequent diagnosis. By generating unprecedented epidemiological evidence in a middle-income country context, this study contributes to the reduction of knowledge gaps about rare tumors in the pediatric population, strengthening local epidemiological surveillance capacity and subsidizing the planning of public policies and health care strategies in the State of Goiás.