Objectives: The aim of this study is to explore the cost analysis of drug delivery therapy services for adults’ population at Ministry of Health in Saudi Arabia by using American Model with local cost. Methods: It is a cross-sectional 6-months analysis of drug distribution services for adult patients conducted in 2016. It was at 300-bed maternity and pediatrics hospital in Riyadh, Saudi Arabia. The cost calculated adults drug therapy management services delivered to 144 beds. The physician prescribed the medications. The pharmacist reviewed and prepared drugs and distributed through the unit dose system, floor stock distribution and discharge medication services. The fast-moving oral and topical medications were included in the study. The cost model was calculated based on variable expenses including personal cost, material and supply cost. The fixed cost was including direct cost, non-salary cost and overhead cost. All cost was used of US dollar currency and local prices. Results: The estimated cost of drug delivery therapy services for all total number adults’ beds per day was (1,191.965 USD). It contained three types; the unit dose system (761.35 USD), drug floor stock distribution system (334.99 USD) and discharge medication system (95.62 USD). The cost of delivery of medicines to single bed per day was (13.99 USD) with the highest estimated cost of delivery from discharge medication (6.37 USD), followed by unit dose services (5.29 USD) and floor stock therapy (2.33 USD). The total estimated annual expenditures of drug distribution services were (435,067.15 USD). Conclusion: In this adults medication therapy services cost-estimation the first study was conducted at MOH in Saudi Arabia. It is an essential necessary element of the Pharmacoeconomic program and implements Saudi’s future vision 2030 for drug therapy health care services.