A modest number of clinics in Oregon and Washington provide MMT maintenance treatment (MMT) services. More than 10,000 clients in each state were followed for 3 years after an initial admission for opiate use between 1993 and 2000. Medicaid clients in both states had far greater access to MMT than their non-Medicaid counterparts, controlling for differences in client characteristics using propensity scores. Months in MMT were associated with much lower arrest rates than time not in treatment, but unexpectedly this was only true for clients participating in MMT for many months. Despite differences in the treatment systems for opiate addiction in these two states observed in previous studies, the current findings generalized across both states.