Introduction. Iron Deficiency Anemia (IDA) is still an important children health problem in Indonesia and wide world. The prevalence of IDA in Indonesia in 2007 according to Survey Kesehatan Rumah Tangga (SKRT) was 61.3 % among 0-6 months infants and 64.8 % among infants 6-12 months aged. IDA in children is associated with neurodevelopmental problem result in impaired of concentration, impaired growth, and decrease of physical activity, creativity, and immunity of the children. Aim. This research objective was to determine the association between medicinal iron supplementation with the occurrence of iron deficiency and anemia in infants and under-2 years-old children. Method. This was a case-control study. The case group was defined as infants 9 months old – 24 months old children with anemia and/or iron deficiency while the control group is infants and children without anemia or iron deficiency at same age. The case group consisted of 34 subjects and the control group consisted of 37 subjects. Data was analyzed with Fisher’s- exact test and the association between factor and outcome was determined as an odds ratio (OR). Result. Iron supplementation was associated with the occurrence of iron deficiency/ anemia in infants and children under 2 years old with p value 0,032. Non-iron supplemented infants and children have 5 times higher possibility to suffer from iron deficiency / anemia (OR= 5.14; CI 95%= 1,02-25,83) compared with supplemented subjects. Conclusion. Iron supplementation was seen can decrease the risk of iron deficiency anemia in infants and under 2 years old children.