OBJECTIVES: ED can be administered based on three different systems – powder based (Po),  open, liquid (Op), and a completely closed (Cl). There are differences in the preparation, installation and delivery and in the diarrhea rates among them.  Our aim was to measure the total costs for each system, considering the resources needed to prepare, delivery administer and discard of each system (hidden costs). METHODS: We measured the human (nurse, nutritionist, auxiliary personnel) resources involved in ED preparations in three hospitals of Brazil. Then, we calculated the costs of the process, based on the minimum official wage for each professional category. After, we added the costs of the diets and materials needed to the infusion. We used as base case a daily need of 1 000Kcal / patient. Additional analyses were performed to include the side effects of ED system. RESULTS: There were differences among the human resources needed for each system. Hidden costs were 63% of the total for Op, 58% for Po and 53% for Cl. Particularly, the nurse time varied from 18 minutes for Po and Op and 5 min for Cl for each infusion. Considering that and average patient would require daily 4 infusions of Po or Op, that represents a total of 72min of nurse time to these systems, against 5 min to Cl. Total daily costs, were Op US$ 62.05; Po US$ 50.75 and Cl US$48.03. If we consider the costs of side effects, such as diarrhea, the costs are: Op US$ 73.42; Po US$ 62.15 and Cl 56.35. This increase in the difference amog the costs is due to a lower incidence of diarrhea in Cl systems. CONCLUSIONS: There are many hidden costs on the ED systems. If we consider them Cl systems are less costly than Op and Po.