To investigate the influence of smoking on peripheral immune cells in patients with acute ischemic stroke. Methods: A total of 165 patients with stroke onset within 72 hours were enrolled in the present study. Baseline clinical and laboratory data were collected. Peripheral blood samples were obtained, and the count and percentages of lymphocyte subsets were analyzed by flow cytometry, allowing for comparisons between individuals who smoked or not. Univariate and multivariate logistic regression analyses were performed for various parameters. Spearman analysis was employed to assess the correlation between smoking intensity and lymphocyte subsets. Results: In patients with acute ischemic stroke, smokers exhibited notably higher count (P<0.001) and percentage (P=0.009) of B cells, as well as an elevated count of T cells (P=0.013) and suppressor T cells (P=0.032) when compared to non-smokers. Univariate logistic regression analysis showed a significant association between smoking and count (OR=3.384, 95% CI 1.621～7.067, P=0.001) and percentage (OR=2.243, 95% CI 1.095～4.596, P=0.027) of B cells, as well as T cell count (OR=2.104, 95% CI 1.055～ 4.196, P=0.035). Furthermore, correlation analysis revealed a positive association between smoking intensity and the count of B cells (P=0.002), the percentage of B cells (P=0.009), and the count of T cells (P=0.012). Con? clusion: Smoking was an independent risk factor of higher count and percentage of B cells, and a higher count of T cells in patients with acute ischemic stroke.