Background: Anemia is a significant health problem in developing countries. Maternal anemia reduces fetal iron stores prior to birth and hence babies born to anemic mothers tend to develop iron deficiency anemia before 6 months which has adverse psychomotor consequences. Aim: The aim of this study was conducted to estimate the prevalence of anemia in exclusively breastfed babies between 3-6 months of age so that we can identify, prevent and treat anemia and its consequences at an early age. Material and methods: This retrospective observational study was done the Department of paediatrics, Nalanda Medical College and Hospital Patna, Bihar, India, for 8 months. Exclusive breastfed term infants aged between 3-6 months of age (90 days to 180 days) who undergone complete blood count (CBC) examination for some minor ailments was included in this study. All the infants were looked for anemia and its severity. Results: Out of 100 infants in the study group, 14 had URI with pallor, 40 had ALRI and another 14 had gastroenteritis with pallor. Three each presented with UTI, Febrile convulsions, Ricketsial fever, septicemia and laryngomalacia. Remaining 17 children had different minor illnesses but none had severe life threatening illness. Among 100 infants, 60 were males and 40 were females. According to age 32, 42 and 26 babies were belonging to 3- 4, 4-5 and 5-6 months respectively. Mean age was 4.3 month and Hb was 9.6 mg/dl. Median Hb was 9.5 mg/dl. A total of 85 children had anemia as per WHO criteria of <11 gm% of Hb, giving a prevalence of anemia of 85%. However if we take 10.5 mg% as cut off value 81 (81%) had anemia and for 10 mg%, 60 (60%) had anemia. Segregating by gender, 57 males and 28 females were anaemic. Conclusion: Exclusively breastfed infants between 3-6 months are at increased risk of anemia. Therefore infants after 3 months should be evaluated for anemia and iron deficiency which is the commonest cause of anemia. Such infants should be supplemented with oral iron in addition to exclusive breast feeding for 6 months, to prevent adverse effects of IDA on infants’ growth and development.