In Indonesia, 96% of children (< 24mo) are breastfed. However, only 42% of children (< 6mo) are exclusively breastfed, as per World Health Organization recommendations. This study estimated the potential economic impact of not breastfeeding (per World Health recommendations) in Indonesia based on infants suffering from attributable diarrhea and PRD. Based on a cost analysis that examined both the healthcare system costs and non-medical costs for children (< 24mo) with diarrhea and PRD, the study found that the healthcare system cost due to not breastfeeding was estimated at US$118 million annually. Additional costs, policy recommendations, and insight into the study design, are reflected in this paper.