INTRODUCTION: Hemolytic disease of new–born due to ABO–incompatibility has become the most common disease in infants at present, consequent to the introduction of routine Rh Ig immunoprophylaxis. It occurs due to ABO blood group incompatibility between the mother and infant. The anti–A or anti–B antibodies of a mother of blood group O, B or A may cross the placenta and sensitize the RBCs of an A, B, or AB infant. HDN/ABO is one of the important cause of neonatal hyperbilirubinemia. Because A and B antigens are widely expressed in a variety of tissues besides RBCs, only minor portion of antibodies crossing the placenta is available to bind to fetal RBCs, in addition fetal RBCs appear to have less surface expression of A or B antigen, resulting in few reactive sites hence the low incidence of significant haemolysis in affected neonates. Nevertheless it can cause a severe haemolytic condition leading to morbidity and mortality, if not detected or controlled early. My aim is to to find out the incidence measure the bilirubin level in new–born and to determine the frequency of ABO incompatibility in HDN. METHODS : 100 cases of Mother and Foetal samples were taken with ‘O’ positive mother and A, B and AB neonates. Blood grouping and others parameters like Hb, bilirubin, reticulocyte counts along with peripheral smear were done. Immunoglobulin study with direct coomb’s test and indirect coombs test were assessed with infants and mother blood. Severity of jaundice with other parameters for immune haemolytic condition were assessed and compared to come to diagnosis. RESULTS :Out of 100 cases 31(31%) had HDN/ABO and all the cases presented with jaundice which is the hallmark of the disease. Various parameters for HDN/ABO include, peak bilirubin level of 18–26mg/dl raising in 1 to 3 days .Lower limit of Hb was 11 gm/dl. Sex distribution shows male preponderance with 22 of 31(70.97%) as against 9 of 31(29.03%) in females. ‘A’ blood group was more preponderant with 17 out of 35 HDN/ABO consisting of 54%.DCT showed only 4 of 31(12.9%) positive in HDN/ABO. Mean reticulocyte count was 7.1.Familial history did not correlate with the disease in this study. CONCLUSION: In conclusion, haemolytic disease of new–born due to ABO incompatibility is a worldwide problem including our county. Increase bilirubin, mild anaemia, increase retic count and peripheral features of spherocytosis aids to early diagnosis. Coombs test in the form of DCT and ICT is not always associated with the disease but have definitive support to diagnosis.