IntroductionIron deficiency anemia (IDA) is still a major global health problem. The prevalence was highest among children under five years, 39.7%, with the most contributing cause being dietary iron deficiency (ID). Reticulocyte hemoglobin equivalent (Ret-He) assesses the amount of hemoglobin in reticulocytes. Ret-He is an easy, inexpensive, and applicable diagnostic parameter of iron deficiency. This study aims to determine the role of Ret-He as a diagnostic parameter of ID and IDA in infants 1-4 months old.Material and methodsThe study was conducted prospectively at 10 Community Health Centers in Banjarbaru, South Kalimantan, from August 2020 to August 2021. Total 403 infants aged 1, 2, 3, and 4 months met the inclusion and exclusion criteria. Venous blood samples were checked for Ret-He, complete blood count, and peripheral blood smears.ResultsThe incidence of ID and IDA in infants 1-4 months were 10,9% and 58,6%. Ret-He cut-off values for iron deficiency and IDA at 1, 2, 3 and 4 months were 22,25 pg, 20,3 pg, 19,05 pg and 17,55 pg; with sensitivity 7,8%, 2,5%, 7,4%, 8,2%; specificity 94,4%, 95,0%, 96,9%, 98,1%; positive predictive value 85,7%, 66,7%, 83,3%, 80,0%, and negative predictive value 18,1%, 19,6%, 33,0%, 53,6%.ConclusionsRet-He can detect iron deficiency and IDA in 1-4 months baby with high specificity and positive predictive value.