The term dyserythropoiesis was originally used in the description of a group of previouslyunrecognised congenital anaemias characterized by pathological alterations of the morphology of erythroblasts.Only a minority of the erythroblasts in normal bone marrow shows dysplastic features such as basophilic stippling, vacuolation of the cytoplasm, irregular nuclei, intercytoplasmic bridges of erythroblasts, Howell-Jolly bodies. Binuclearity, involving late erythroblasts in the bone marrow can be found occasionally only, multinuclearity is never present. Dyserythropoiesis is considered to be present when the proportion of erythroblasts showing dysplastic features is greater than normal or when features not seen in normal bone marrow such as megaloblastoid changes, internuclear chromatin bridges or other anomalies are present. There are several congenital and acquired disorders in which there is dyserythropoiesis present. Congenital dyserythropoietic anaemias (CDA) are characterized by morphological alterations of erythroblasts, ineffective erythropoiesis and in some increased tendency to iron overload. Heimpel and Wendt classified CDA patients into one of three types designated types I, II and III. Subsequently it has become apparent that there are CDAs that did not fit the classical three types. They have been denominated CDA-IV or CDA variants. The paper summarizes the up to day knowledge of dyserythropoiesis and of congenital dyserythropoietic anaemias especially.

        Key words: dyserytropoéza, CDA (I – III)