Background: Hereditary Elliptocytosis (HEllip) is a congenital haemolytic anemia (HA) of predominantly dominant transmission, with heterogenous phenotype, caused by quantitative / qualitative alterations of erythrocyte membrane proteins. Most cases do not present anemia, only ellipticals in the peripheral blood smear (PBS);10 to 20% have HA of variable severity, and may present with splenomegaly. Hereditary pyro poikilocytosis (PPH) is a serious form of HEllip, the most severe phenotypes of which are associated with mutations in the self-association contacts of αβ-spectrin. In the neonatal period, a transient poikilocytosis (PTN), with significant HA and marked anisopoikilocytosis, can be observed and be confounded with PPH. Clinical evolution allows the differentiation. PTN is associated with the predominance of HbF in this age group, with reduced affinity for the 2,3-DPG erythrocyte enzyme. From the first year of life, with the decline of HbF, the child will present a lighter phenotype typical of HEllip. Aims: Description of a clinical case of a rare form of congenital hemolytic anemia. Methods: Description in the form of a clinical case Results: Male infant, referred to the consultation at 7 months for microcytic / hypocromic anemia with poor response to iron oral suplementation. The research of his personal background revealed a hospitalizationin Neonatal Intensive Care Unit due to neonatal asphyxia and septic shock in second day of life. At this point he presented worsening of anemia (Hb) 9.2 g/dL, reticulocytosis and evidence of haemolysis, PBS with severe anisopoikilocytosis, fragmented RBC, with numerous elliptocytes and micro spherocytes. At this time he was medicated with oral iron, with a poor response in the Hb value. Due to the lack of response to the established oral iron, it was referenced to the consultationat 7 months. Hb studies (High performance liquid chromatography – HPLC) were normal and screening tests for hereditary spherocytosis were negative. Due to haemolytic conditions, with marked microcytosis, and the presence of marked anisopoikilocytosis in PBS, the most probable initial hypothesis was PPH. Sequencing of the STAPA1 gene excluded polymorphisms, such as αLELY. With about 18 monthsof age initiated spontaneous improvement of anemia and normalization of haemolysis parameters. In the last evaluation, he maintains excellent development, with Hb 11.3 g/dL, MCV 75.9fL, MCH 22.5pg, RDW 21 and reticulocytes 70G/L. Summary/Conclusion: The authors intend to alert to the difficulty to distinguish between these two entities, which, despite having a similar presentation in the neonatal period, have a different clinical course, emphasizing the importance of a careful follow-up during the first months/year of life, avoiding parent's distress.