BackgroundBlack individuals with substance use disorders (SUD) are less likely to receive effective treatment and more likely to be incarcerated compared to White individuals. Despite this, research documenting racial disparities in healthcare use among people with SUD releasing from prison is limited. ObjectivesThe goals of this study are to: 1) assess racial disparities in Medicaid enrollment among individuals released from prison with a history of substance use; and 2) characterize racial disparities in outpatient service use, emergency department (ED) use, and receipt of medication for opioid use disorder (MOUD) among those who do enroll in Medicaid. MethodsThis study included individuals with a history of substance use that were released from Wisconsin state correctional facilities from April 2015 through June 2017. Medicaid enrollment and claims data were analyzed to compare healthcare utilization 6 months post-release between individuals identifying as Black, White, or other races. The total sample included 15,621 prison releases among 14,400 unique persons with a history of substance abuse. ResultsAmong the 15,621 prison releases, 10,836 (69.4%) were enrolled in Medicaid in the month of release. The proportion of prison releases among individuals of other races who enrolled in Medicaid (506/934, 54.2%) was significantly lower than the proportion among Black individuals (3679/5306, 69.3%) and White individuals (6651/9381, 70.9%). Among the subset of 7685 releases enrolled in Medicaid for 6 months post-release, 5040 (65.6%) had an outpatient visit within 6 months; 73.9% of White, 51.3% of Black, and 66.9% of other individuals. Relative to White individuals, Black individuals were 0.324 times less likely (P < 0.001) and individuals of other races were 0.591 times less likely (P = 0.004) to have an outpatient visit. Of the 7685 releases, 1016 (13.2%) had an ED visit within 6 months; 12.0% of White, 13.8% of Black and 25.1% of other individuals. Relative to White individuals, Black individuals were 1.23 times more likely (P = 0.019) and individuals of other races were 2.64 times more likely (P < 0.001) to have an ED visit. Black individuals were 0.100 times less likely (P < 0.001) and individuals of other races were 0.435 times less likely (P = 0.016) to receive MOUD post-release compared to White individuals. ConclusionsBlack adults with a history of substance use are significantly less likely than White adults to use non-emergency outpatient services after release from incarceration. Improving equitable access to outpatient services is needed to reduce health disparities across racial groups.