Background and objectives Hypertension is one of the most important risk factors for cardiovascular and cerebrovascular events. Inflammatory processes occupy an important place in the pathogenesis of hypertension. Many studies have studied inflammatory markers responsible for the onset of hypertension and organ damage. In this study, we investigated whether the systemic immune-inflammation index (SII) (platelet x neutrophil/lymphocyte), - one of the new inflammatory markers - can be used to predict cerebrovascular events in hypertensive patients. Methods Ambulatory blood pressure monitoring results between January 2019 and June 2020 of approximately 379 patients followed up with hypertension were retrospectively analyzed. These patients were divided into two groups as with or without a previous cerebrovascular event in the analyzed database. In all patients, complete blood count and biochemistry test results just before the cerebrovascular event were found from the database. SII, atherogenic index, neutrophil-lymphocyte ratio were calculated from the complete blood count. Forty-nine patients with stroke (group 1: 12.9%; mean age: 64.3 +/- 14.6) and 330 patients without stroke (group 2: 87.1%; mean age: 50.8 +/- 14.4). Results Ambulatory blood pressure measurements were lower in group 1. Lipid parameters were also lower in this group. Receiver operating characteristic curve analysis showed that SII had a sensitivity of 85.7% and specificity of 84.8 % for stroke in individuals who participated in the study when the cutoff value of SII was 633.26 x 10(3) (P = 0.0001) area under curve (95%); 0.898 (0.856-0.941). In multivariate logistic regression analysis, age and SII were significantly associated with a higher risk of stroke. Age, (hazard ratio:1.067; 95% CI, 1.021-1.115), SII (hazard ratio:1.009; 95% CI, 1.000-1.009), respectively. Conclusions In conclusion, SII is a simple, useful new inflammatory parameter for predicting stroke from hypertension. We found that the high SII levels increase the risk of stroke in hypertensive patients.