- AIMS: To determine whether infection with Helicobacter pylori is a significant risk factor for stroke. SUBJECTS: A total 467 in-patients with clinical evidence of acute ischaemic stroke and 388 healthy controls with no evidence of cerebrovascular disease. METHODS: This was a case control study. The prevalence of Helicobacter pylori was measured by enzyme-linked immunosorbent assay in stroke patients and controls. A positive titre was defined as >15 U/ml and relationship with circulating plasma fibrinogen and social depravation was expressed using the Townsend Index. RESULTS: There were significantly more Helicobacter pylori positive individuals (274/398 (69%)) in the cases compared to the controls (206/352 (58.5%)). Fibrinogen levels were also significantly higher in Helicobacter pylori positive (mean 4.14, standard deviation 1.33) than negative individuals (mean 3.78, standard deviation 1.28). The association between Helicobacter pylori and stroke was lost in a logistic model controlling for socio-economic status. Furthermore, fibrinogen levels were not associated with Helicobacter pylori status in a linear regression model controlling for socio-economic status. CONCLUSIONS: Infection with Helicobacter pylori is associated with an increased risk of stroke and increased fibrinogen levels but these findings can be attributed to a confounding effect of socio-economic status.