There is increasing evidence that acute bacterial and viral infection represent trigger factors that temporarily elevate the risk of ischemic stroke. During and after influenza epidemics vascular death rates and hospitalizations for stroke are increased. Influenza vaccination is an effective measure to reduce hospitalization and mortality in the elderly and work incapacity in adults of working age. Results of several observational studies support the hypothesis that influenza vaccination is associated with reduced odds of stroke. As randomized studies are lacking, a causal role of influenza vaccination in stroke prevention is not proven, however. According to current guidelines in many countries, that recommend the vaccination in all patients with chronic vascular disease, all patients with a history of stroke or TIA should receive an influenza vaccination annually. Furthermore, patients with diabetes mellitus or with a combination of risk factors that increase stroke risk should obtain the vaccination. In addition, there is evidence from observational data that the neuraminidase inhibitor oseltamivir reduces the risk of stroke within 6 months after influenza infection.