Background: It is currently unknown if premature atrial contractions (PACs) detected on the routine screening electrocardiogram are associated with an increased risk of ischemic stroke. Methods: We examined the association between PACs and ischemic stroke in 22,975 (mean age 64 ± 9.2; 56% women; 40% black) participants from the Reasons for Geographic and Racial Differences in Stroke study. Participants who were free of stroke at baseline were included. PACs were detected from centrally read electrocardiograms at baseline. Cox regression was used to examine the association between PACs and ischemic stroke events through March 31, 2014. Results: PACs were present in 1,687 (7.3%) participants at baseline. In a Cox regression model adjusted for stroke risk factors and potential confounders, PACs were associated with an increased risk of ischemic stroke (hazards ratio (HR) 1.34, 95% CI 1.04-1.74). The relationship was limited to non-lacunar infarcts (HR 1.42, 95% CI 1.08-1.87), and not lacunar strokes (HR 1.01, 95% CI 0.51-2.03). An interaction by sex was detected, with the association between PACs and ischemic stroke being stronger among women (HR 1.82, 95% CI 1.29-2.56) than men (HR 1.03, 95% CI 0.69-1.52; p-interaction = 0.0095). Conclusion: PACs detected on the routine electrocardiogram are associated with an increased risk for non-lacunar ischemic strokes, especially in women.