Background: Cigarette smoking is a well-known risk factor for ischemic and hemorrhagic stroke. We evaluated the impact of smoking status on hematoma expansion and clinical outcome in patients with primary intracerebral hemorrhage (ICH). Methods: This is a post hoc exploratory analysis of Antihypertensive Treatment at Acute Cerebral Hemorrhage(ATACH)-2 trial. Patients with ICH were randomized into intensive blood pressure lowering(SBP: <139 mmHg) versus Baseline characteristics were compared based on smoking status. Analysis of outcome measures was adjusted for covariates included in the ATACH-2 primary analysis or those associated with smoking status. Results: Of total of 914 patients in the trial with known smoking status, 439 (48%) patients were ever-smokers (264 current smokers and 175 former smokers). Current and former smokers were younger and more likely to be male. There was no difference in the baseline Glasgow Coma Scale(GCS) score and initial hematoma size based on smoking status. Ever-smokers had higher rate of thalamic hemorrhage (42% vs 34%) and intraventricular hemorrhage (29% vs 23%); this rate was highest among former smokers (49% and 35%, respectively). Ever-smokers had higher rate of hematoma expansion in 24 hour [adjusted RR (95% CI): 1.46; (1.05 -2.03)] compared to non-smokers after adjusting for confounding factors. There was no significant difference in the rate of death and disability at 90 days between the two groups [adjusted RR; (95% CI): 1.18; (0.93 -1.50)]. Conclusions: Our analysis demonstrates cigarette smoking as an independent predictor for hematoma expansion. There was no significant difference in death and disability based on smoking status.