OBJECTIVES: The aim of this study is to examine the estimation trends in utilization, spending, and prices of opioid medications for the US Medicaid population. METHODS: A retrospective study was designed to explore the opioid medication utilization of the Medicaid patients from 1991 to 2017. The data was extracted from the national Medicaid pharmacy claims data collected by the Center for Medicaid/Medicare Services. Study opioid medications included seven groups which are Fentanyl, Meperidine, Morphine, Hydromorphone, Oxymorphone, Hydrocodone and Hydrocodone combination, and Oxycodone and Oxycodone combination. Spending (reimbursement amount) and number of prescriptions were calculated annually for each medication. Per prescription price was calculated as the spending divided by the number of prescriptions. RESULTS: The total number of all opioid prescriptions increased in 1991 from 1,991,239 to 18,457,851 in 2017. The total utilization of Hydrocodone and Hydrocodone Combination from 1991 to 2017 was 225,243,046 prescriptions which are the highest utilization among all other opioids while Oxycodone and Oxycodone Combination were the second opioid group medications with 103,105,010 prescriptions. The total spending of Oxycodone and Oxycodone combination were $ 6,970,025,989 which represent the highest spending amount compared to other opioid drugs. Moreover, the total spending of Hydrocodone and Hydrocodone combination was $ 3,015,962,956 while the total spending of Morphine was $1,861,253,687. Meperidine spending was $ 91,337,371 which was the lowest amount among all opioid medications. The estimated price of Hydrocodone and Hydrocodone combination did not exceed $ 20.00 per prescription. The price of Fentanyl per prescription dropped in 2008 from $ 317.39 to around $100.00 in 2017. CONCLUSIONS: The utilization and spending of opioid medications were increasing in the Medicaid population. This high rate of utilization may lead to addiction and high health care cost.