Aim: 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 Upgraded Department of Paediatrics, Patna Medical College & Hospital, Patna, Bihar, India, from feb 2017 to July 2018. 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: Total 550 infants aged 3-6 months attended OPD during study period. Out of them, 150 infants had their CBC done for various reasons and for pallor. After excluding 40 babies as per our exclusion criteria, 110 infants matched the selection criteria and remained as study group. Among 110 infants, 65 were males and 45 were females. According to age 35, 47 and 28 babies were belonging to 3-4, 4-5 and 5-6 months respectively. Mean age was 4.5 month and Hb was 9.9 mg/dl. Median Hb was 9.6 mg/dl. A total of 92 children had anemia as per WHO criteria of <11 gm% of Hb, giving a prevalence of anemia of 83.64%. However if we take 10.5 mg% as cut off value 85 (77.27%) had anemia and for 10 mg%, 69 (62.73%) had anemia. Out of 92, 31 (88.57%) babies with age of 3-4 months, 40 (85.11%) aged 4-5 months and 21 (75%) aged 5-6 months had anemia. out of 92, 62 males and 30 females were anemic. Conclusion: we concluded that the 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.