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Introduction Ruptured intracranial aneurysms (RIAs) are one of the most lethal cerebrovascular pathologies, with high mortality and lasting disability among survivors. Management is complicated by patient comorbidities and aneurysm anatomy, which may determine both the feasibility and safety of microsurgical and endovascular strategies. One challenging aneurysmal feature is branch vessel incorporation (BVI), where an artery originates from the aneurysm dome or neck. This adds complexity to treatment and increases the risk of ischemia if the incorporated vessel is occluded. While BVI is known for its challenge in treatment, little is known about what factors influence this morphology. Smoking is one of the strongest modifiable risk factors for aneurysm formation and rupture, but its relationship to aneurysm morphology has not been well studied.Methods Single-center retrospective review of patients aged 18 or older treated for ruptured intracranial aneurysms between January 2016 and December 2024. Treatment modalities included microsurgical clipping and endovascular techniques. Angiograms were used to determine procedural decisions and aneurysm morphology. Medical records were used to obtain patient demographics, comorbidities, lifestyle factors, and presenting symptoms. Univariate associations were tested using χ 2 analysis, and multivariable logistic regression was performed to identify independent predictors of BVI while adjusting for age, sex, and other comorbidities. All statistical work was carried out in STATA SE version 18.0, R Studio version 2025.5.1.513,and Python version 4.3.Results Out of the 162 patients treated for RIAs, 52 patients (28.1%) had aneurysms with branch vessel incorporation. Current smokers have the highest representation with 61.7% of their aneurysms incorporating a branch vessel compared to 36.4% of former smokers and 27.1% of non-smokers. An association between smoking status and branch vessel incorporation was detected (p=0.009). On multivariable regression, active smoking remained an independent predictor of BVI with an odds ratio of 2.64 (95% CI 1.05-6.67, p=0.04). Other comorbidities such as hypertension, diabetes, or hyperlipidemia and demographics such sex or race had no observable association. These findings suggest that active smoking is not only a driver of aneurysm rupture risk but also linked to more complex aneurysm anatomy. The frequency of BVI in this cohort emphasizes its importance in both treatment planning and outcome prediction.Conclusions Smoking stood out as an independent predictor of BVI in ruptured aneurysms. Active smokers were more than twice as likely to have this morphological characteristic. While larger multicenter data will be needed to confirm this finding, our data suggest smoking may shape not only rupture risk but also the morphology that influences RIA care.Disclosures A. Naqvi: None. A. Gajjar: None. A. Custozzo: None. A. Paul: None.