The incidence of postoperative stroke ranges from 0.08% to 0.7% in noncardiac surgery. Recently, the PeriOperative ISchemic Evaluation (POISE) study reported an incidence of postoperative stroke of 1% in patients scheduled for noncardiac surgery when β blockers were initiated immediately before surgery. To assess the association between chronic β-blocker use and postoperative stroke in noncardiac surgery, we undertook a case-control study among 186,779 patients who underwent noncardiac surgery from 2000 to 2008 at the Erasmus Medical Centre. Patients who were undergoing intracerebral surgery or carotid surgery or who had head and/or carotid trauma were excluded. The case subjects were 34 patients (0.02%) who had experienced a stroke within 30 days after surgery. Of the remaining patients, 2 controls were selected for each case and were stratified according to calendar year, type of surgery, and age. For cases and controls, information was obtained regarding β-blocker use before surgery, the presence of cardiac risk factors, and the use of other cardiovascular medication. The use of β blockers was as common in the cases as in the controls (29% vs 29%; p = 1.0). The adjusted odds ratio for postoperative stroke among β-blocker users compared with nonusers was 0.4 (95% confidence interval 0.1 to 1.5). Similar results were obtained in the subgroups of patients stratified according to the use of cardiovascular therapy and the presence of cardiac risk factors. In conclusion, the present case-control study has shown no increased risk of postoperative stroke in patients taking chronic β-blocker therapy.