OBJECTIVES: To determine if poor adherence to dabigatran is associated with an increased risk of stroke. METHODS: A case-control study, nested in a population of dabigatran users, was conducted within an integrated health care delivery system. Eligible patients had a diagnosis of atrial fibrillation (AF) and a prescription for dabigatran between November 2010 and June 2015. Strokes, based on a primary hospital discharge diagnosis after starting dabigatran, were the case defining events. In addition, the stroke had to occur while the patient was a current or recent (within 30 days) user of dabigatran based on pharmacy dispensing records. Up to 4 controls were matched to each case using age, gender, duration of dabigatran use and CHADS2 score (< 3 or ≥ 3). Adherence was measured by medication possession ratio (MPR) for the year prior to the stroke date (1-yr MPR) in cases, or the equivalent event date in controls.  MPR <0.8 was defined as poor adherence. A conditional logistic regression model was used to evaluate the association between adherence and stroke events. Secondary models include peripheral vascular disease (PVD) as a confounder. RESULTS: A total of 1833 AF patients were identified and 49 strokes occurred in this population. After applying exclusion criteria, 23 stroke cases remained eligible and these were matched to 84 controls. Matching produced populations with similar characteristics. Overall, the mean age was 73.1 years, 75.7% were males and the duration of dabigatran therapy was 630 days.  For cases, 39.1% had poor adherence vs. 11.9% in controls. The odds ratios (OR) for stroke, associated with 1-yr MPR <0.8 was 3.5 (95% CI; 1.1-11.5). The OR with PVD in the model was still elevated but no longer significant. CONCLUSIONS: In this small study, patients with poor adherence to dabigatran had a higher odds of stroke although the association was not independent of PVD status.