Background: Intracerebral hemorrhage (ICH) causes death or disability and the incidence increases with age. Knowledge of acute hemostatic function in patients with ICH without anticoagulant and antiplatelet therapy is sparse. Increased knowledge of the coagulation profile in the acute phase of ICH could improve acute treatment and recovery. We investigated coagulation at admission and changes in coagulation during the first 24 hours after symptom onset. Methods: Enrolled were 41 ICH patients without anticoagulant or antiplatelet therapy admitted to Aarhus University Hospital, Denmark. Blood samples were collected at admission, 6, and 24 hours after symptom onset. Thromboelastometry (ROTEM), thrombin generation, and thrombin-antithrombin (TAT) complex were analyzed. Clinical outcome was evaluated using the National Institute of Health Stroke Scale, the Modified Rankin Score, and mortality. Results: At admission, compared with healthy individuals, ICH patients had increased maximum clot firmness (EXTEM P <.0001; INTEM P <.0001; FIBTEM P <.0001), increased platelet maximum clot elasticity (P <.0001) in ROTEM, higher peak thrombin (P <.0001) and endogenous thrombin potential (P =.01) in thrombin generation, and elevated TAT complex levels. During 24 hours after significantly, while thrombin generation showed decreased peak thrombin (P <.0001) and endogenous thrombin potential (P <.0001). Coagulation test results did not differ between patients when stratified according to clinical outcome. Conclusions: ICH patients without anticoagulant or antiplatelet therapy demonstrated activated coagulation at admission and within 24 hours after symptom onset.