Background and Purpose-Intracerebral hematomas (ICHs) often increase in size in the initial hours. It is unknown whether expansion of ICHs after aneurysmal rupture in the acute phase is always a sign of rerupture of the original aneurysm. Methods-We included patients with an ICH from a ruptured aneurysm who underwent computed tomography imaging within 24 hours of symptom onset and a repeat computed tomography within 48 hours. Hematoma growth was considered present when there was a 33% increase in hematoma volume, as assessed by the ABC/2 method. Clinical and radiologic characteristics were compared between patients with ICH growth, with and without clinical signs of rerupture. Rerupture was defined as a sudden deterioration in the level of consciousness in the absence of ventricular enlargement or a systemic cause. Results-Hematoma expansion within 48 hours after onset occurred in 12 of the 49 included patients and was preceded by clinical evidence of rerupture in 6 of these 12 patients. Of the 6 patients without an evident rerupture, 3 had no clinical deterioration, 1 had respiratory failure due to pneumonia, another had temporal brain herniation, and the last had acute hydrocephalus. Conclusion-Only