The use of health services by prisoners during their incarceration and after their return to the community impacts the U.S. health care system and health care costs associated with this system. These health care costs are expected to increase over the next decade as more prisoners return to their communities. The current study prospectively examines the use of high-cost health care services-emergency room visits and hospitalizations-among 565 male drug-abusing prisoners about 1 year after prison release. A series of structural equation models were used to examine predisposing factors, including health status and drug use, and to estimate the frequency of high-cost health service utilization. As expected, health status was the most robust predictor of high-cost health services. However, the finding that drug abuse had nonsignificant relationships with high-cost health services utilization was not expected. Discussion focuses on health care service issues and health problems as prisoners' transition from prison to the community.