CagA-positive Helicobacter pylori infection has been found to be associated with a first-ever atherosclerotic stroke. The aim of this study was to investigate whether these strains represent an independent risk factor for recurrent atherosclerotic stroke. We performed a longitudinal study of patients with a first-ever large vessels stroke and resulted positive at H. pylori serology. Patients had clinical examination 1 month after the acute event, and were subsequently visited or contacted by telephone up to 3 years at 6-month intervals. Sera obtained at the time of enrollment were frozen and analyzed for the presence of anti-CagA antibodies at the end of the study. The primary outcome event was any fatal or nonfatal stroke after the index stroke. One hundred seventy H. pylori-positive patients were included (n = 68 CagA positive and n = 102 CagA negative). No significant difference regarding age and other stroke risk factors was detected. According to Kaplan-Meier survival analysis, CagA-positive patients showed a significantly higher risk for stroke recurrence than CagA-negative ones (45.6% vs 17.6%; p < .001). Difference in the rate of recurrent stroke between the two groups persisted after Cox regression analysis taking into account possible confounding factors (hazard ratio = 3.5; 95% CI = 1.9-6.4; p < .001). Infection with H. pylori CagA-positive strains increases the risk of recurrent atherosclerotic stroke. Seropositivity determination should be performed in order to identify high-risk patients requiring a strict clinical surveillance, and the possible beneficial effect of eradication therapy should be evaluated.