AIMSTo evaluate the role of blood and bone marrow findings in the diagnosis of congenital dyserythropoietic anaemias type I and type II. SETTINGS AND DESIGNDyserythropoietic anaemia is suspected when there is a suboptimal reticulocyte response for the degree of anaemia. Congenital dyserythropoetic anaemias are a group of rare hereditary disorders of hematopoiesis. It is believed that CDA is often under diagnosed. Knowledge of CDA workup in a patient of haemolytic anaemia is often rewarding. MATERIALS AND METHODSAll the cases diagnosed as CDA at a tertiary paediatric centre were reviewed with respect to clinical and serological data, peripheral smear and bone marrow study findings. The haematological changes in CDA were analyzed with respect to the diagnosis. RESULTS AND CONCLUSIONThe light microscopic findings of the peripheral smear and bone marrow aspirate were found to be highly specific for the diagnosis of CDA. Significant differences were also noted between type I and type II CDA.