The systemic inflammatory response index (SIRI) is a well-known marker of systemic inflammation reflecting the body's inflammatory/immune state. The study aimed to evaluate the relationship between the SIRI on admission and aneurysmal subarachnoid hemorrhage (aSAH)-associated pneumonia and compare with other currently used bio-markers. We reviewed 562 successive patients with aneurysmal SAH who underwent endovascular treatment between January 2019 and September 2021. ASAH-associated pneumonia was diagnosed using the modified Centers for Disease Control and Prevention criteria. The SIRI on admission was calculated as monocyte count x neutrophil count / lymphocyte count. Multiple logistic regression models were used for data analysis. A total of 158 (28.11%) patients developed aSAH-associated pneumonia. Using the Multiple logistic regression analysis, a notable dose-response association was found between the elevated SIRI (fourth quartile) and aSAH-associated pneumonia (adjusted odds ratio = 6.759; 95% confidence interval [CI], 3.280-13.930; p < 0.001 [p for trend < 0.001]). The SIRI (0.701, 95% CI: 0.653-0.749) presented a higher area under the curve (AUC) than systemic immune- inflammation index (SII) (0.669, 95% CI: 0.620-0.718) (p = 0.089); neutrophil-to-lymphocyte ratio (NLR) (0.665, 95% CI: 0.616-0.714) (p = 0.035) and platelet-lymphocyte ratio (PLR) (0.587, 95% CI: 0.534-0.641) (p < 0.001). A higher SIRI on admission was associated with aSAH-associated pneumonia, which may guide further clinical trials of prophylactic antibiotic therapy.