OBJECTIVES: Opioid Use Disorder (OUD) is characterized by episodes of relapse and remission. Relapse is a key outcome and quality metric in OUD, but has no specific diagnosis code. This study examined different approaches to measuring relapse in claims data. METHODS: Service-based indicators of opioid relapse were defined in several measures. The conservative measure (CM) included any of the following: diagnosis of continuous or episodic dependence following a dependence in remission diagnosis; hospitalization with a primary opioid-related diagnosis; detoxification with any opioid-related diagnosis; or emergency services with any opioid-related diagnosis. Inclusive measures (IMs) included the CM or any of the following indicators: hospitalization with a secondary diagnosis of opioid overdose; pharmacy claim for narcotic pain medications (NPMs) without indication of trauma/surgery 7 days prior; pharmacy claim(s) for NPMs covering >30 consecutive days; or abruptly stopping buprenorphine without taper. Relapse rates were measured among OUD patients initiating buprenorphine treatment in the MarketScan databases (2008-2014) and rates compared to the literature to assess measure feasibility. RESULTS: Relapse rates 6 months post-treatment initiation ranged from 7.1% (CM) to 38.1% (IM) in Commercial patients (N=22,563) and 6.0% (CM) to 44.0% (IM) in Medicaid patients (N=7,811). Among the IM indicators, abrupt discontinuation was observed in 23.1% of Commercial patients and 26.6% of Medicaid patients. NPM claims without trauma/surgery were observed among 9.5% of Commercial and 16.7% of Medicaid patients. NPMs covering >30 consecutive days were observed among 9.4% of Commercial and 8.8% of Medicaid patients. CONCLUSIONS: Relapse rates varied widely depending on the measure used.  The literature similarly includes variation in rates due to measurement differences between studies.  This highlights the need for a consistent definition of relapse in claims-based studies, the evidence-based utilization of defined measures, and future research targeting the validation of claims-based markers of opioid relapse.