BACKGROUND AND PURPOSE Outpatient statin use reduces the risk of recurrent ischemic stroke among patients with stroke of atherothrombotic cause. It is not known whether statins have similar effects in ischemic stroke caused by atrial fibrillation (AFib). METHODS We studied outpatient statin adherence, measured by percentage of days covered, and the risk of recurrent ischemic stroke in patients with or without AFib in a 21-hospital integrated healthcare delivery system. RESULTS Among 6116 patients with ischemic stroke discharged on a statin over a 5-year period, 1446 (23.6%) had a diagnosis of AFib at discharge. The mean statin adherence rate (percentage of days covered) was 85, and higher levels of percentage of days covered correlated with greater degrees of low-density lipoprotein suppression. In multivariable survival models of recurrent ischemic stroke over 3 years, after controlling for age, sex, race/ethnicity, medical comorbidities, and hospital center, higher statin adherence predicted reduced stroke risk both in patients without AFib (hazard ratio, 0.78; 95% confidence interval, 0.63-0.97) and in patients with AFib (hazard ratio, 0.59; 95% confidence interval, 0.43-0.81). This association was robust to adjustment for the time in the therapeutic range for international normalized ratio among AFib subjects taking warfarin (hazard ratio, 0.61; 95% confidence interval, 0.41-0.89). CONCLUSIONS The relationship between statin adherence and reduced recurrent stroke risk is as strong among patients with AFib as it is among patients without AFib, suggesting that AFib status should not be a reason to exclude patients from secondary stroke prevention with a statin.