Introduction: Langdon Down syndrome (Trisomy 21) is the most common genetic syndrome compatible with survival. Down syndrome is a chromosomal condition characterized by the presence of an additional copy of the genetic material on chromosome 21, either in full (trisomy 21) or partially, due to a translocation.

Objective: The importance of early detection of Down's Syndrome and highlighting the complications caused by this syndrome.
Material and methods: In our study, we analyzed the case of a premature LBW (Low Birth Weight), SGA (small gestational age), female, gestational age-36 weeks, birth weight 1800 grams, from a dispensary pregnancy with morphology performed and a double test, diagnosed with Down syndrome, the examination laboratory paraclinic establishes the diagnosis of acute myeloid leukemia. He is transferred to a pediatric oncohematology clinic and the diagnosis of myeloid leukemia is confirmed, for which chemotherapy is initiated.

Conclusion: The prognosis of congenital leukemia depends on the immunocytological form and the tolerance of the newborn to cytostatic therapy. Most of the time, their evolution is unfavorable, leading to death due to hemorrhages and infections that may occur.