Background: The association between periodontal inflammation and non-fatal stroke is still controversial and limited to evidence in Western countries. The aim of this study was to investigate whether periodontitis is independently associated with non-fatal stroke in Korean adults. Methods: A case-control study was conducted on 265 non-fatal chronic stroke cases at the National Rehabilitation Center, Seoul, Korea, and 214 non-stroke population controls. Medical specialists diagnosed stroke by using brain imaging from magnetic resonance imaging and/or computerized tomography. A dentist recorded the clinical attachment level (CAL), the distance between the cemento-enamel junction and the probed base of the periodontal pocket, using a University of North Carolina-15 manual probe. An interview assessed 17 sociodemographic, behavioral, systemic/oral health-related possible confounders. Multiple logistic regression analysis was used to evaluate the association between periodontitis and stroke while controlling for age, gender, income, education, smoking, drinking, history of systemic disease, body mass index, familial cardiovascular risk factors, and oral health behaviors. Subgroup analyses were also performed. Results: Stroke was strongly associated with periodontitis (presence of CAL >= 6 mm): the odds ratio was 4.0 (95% confidence interval: 2.3 to 7.0) after controlling for all possible confounders. The association with periodontitis (tertiary percentage of CAL >= 5 mm) had a dose-response effect. The association between periodontitis and stroke was higher among adults younger than age 60 (6.0 versus 2.6) and normotensives (4.8 versus 3.2). Conclusion: Our data suggested that periodontitis is independently associated with non-fatal stroke, and its impact seems to be greater among younger or normotensive Korean adults.