Abstract : Cancer in children and adolescents represents only a small fraction of the global cancer burden. However, the different characteristics of adult cancers require the construction of large-scale studies, conducted mainly on a national and even international scale, in order to collect statistically significant data. Our research is part of this effort to provide a reference of knowledge on this type of cancer in Morocco. This is a descriptive retrospective epidemiological study at the two public oncology centers from the records of patients under 20 years of age with cancer diagnosed between January 2014 and December 2018 at the oncology center in Marrakech and between January 2014 and 30/06/2019 at the oncology center in Agadir. Data collection concerned gender, age, origin (city), setting (urban/rural and cancer location. The data were entered and analyzed on SPSS version 24. The incidence of cancer in children and adolescents under 20 years of age was estimated at (7.26/100 000) in the Marrakech Safi region and (8.87/100 000) in the Souss Massa region. They represented respectively 2% and 3% of all registered cases. Among children aged between 0 and 14 years, the incidence of cancer in the global population is estimated at (4.17/100,000) in the Marrakech Safi region and (5.49/100,000) in the Souss Massa region. They represented respectively 1% and 1.6% of all registered cases. The patients are mainly of both sexes without dominance of one over the other, coming from urban areas and from rural areas. Among the most frequent types of cancers among cancer patients under 20 years of age are leukemia, brain and nervous system, bone, Hodgkin's lymphoma. This study has increased knowledge of childhood and adolescent cancers in Morocco and accelerated research towards a better understanding of the most likely risk factors and to strengthen prevention efforts.