OBJECTIVES:  To explore the estimation of cost calculations for delivery drug therapy services for pediatrics by using American Model with local cost. METHODS:  It is a cross-sectional 6-months 2016 analysis of drug distribution services for pediatric. It was at 300-Bed Maternity and Pediatrics Hospital in Riyadh, Saudi Arabia. The cost calculated pediatrics drug therapy management services delivered to 144 beds. The physician prescribed the medications. The pharmacist reviews and prepared drugs and distributed through unit dose system, floor stock distribution, and discharge medications services. The medications prepared through ASHP standards and facilities. The fast moving oral and topical medications included in the study. The cost Model calculated based on variable expenses including personal cost, material, and supply cost. Fixed cost was including direct cost, non-salary cost, and overhead cost. All cost used of US dollar currency and local prices. RESULTS: The estimated cost of Delivery of drug therapy services for all total number adults beds per day was (1,214.72 USD). It consisted of three types; the unit dose system (771.9 USD), drug floor stock distribution system (350.34 USD), and discharge medication services (92.5 USD). The majority of cost came from overhead cost, and material and supply in floor stock services and discharge medication delivery; while the personal cost in unit dose services delivery. The total estimated annual expenditures of Drug distribution services were (443,371.83 USD). The highest budget expenditures from unit dose services 63.54 % (281,743.01 USD), followed by floor stock medication delivery 28.8 % (127,872.64 USD), and discharge drug therapy 7.6 % (33,756.17 USD) CONCLUSIONS: The estimation cost of delivery pediatrics drug therapy is the first study in the Middle East, Gulf countries, and Saudi Arabia. It is basic element of cost calculation of Pediatrics -related health care services.