Hypertensive intracerebral hemorrhage is one of the most common cause of death in Korea and usually considered as a monophasic event. But recently acute expansion of the hematoma within an hour to a day, has been reported as a cause of severe neurological deterioration and death. To know the incidence and risk factors of acute expansion of the hematoma in hypertensive intracerebral hemorrhage, the authors retrospectively analysed 96 hypertensive intracerebral hemorrhage patients who were admitted to Minjoong hospital from January 1997 to December 1998. Neurological examination with Glasgow Coma Scale and first computed tomography (CT) scan were performed as soon as possible after arrival. Then second CT scan was performed within an hour to a day before the operation. Blood sample was taken within an hour for routine laboratory examination including liver function and coagulation test. The amount and shape of hematoma on CT scans were carefully measured to know whether acute expansion was occurred or not. The patients who have acute expansion of the hematoma were 15 patients (15.6%). Expansion of the hematoma was not correlated with sex, age, site, shape, or amount of hematoma statistically. But thalamic hematoma in location, irregular shape of hematoma, or large amount of hematoma has a tendency of acute expansion. The time of onset to arrival, initial systolic pressure, liver dysfunction and history of heavy alcohol drinking were correlated with acute expansion statistically (p<0.05). The shorter the time of onset to arrival and the higher initial systolic pressure, the more the incidence of acute expansion of the hematoma significantly. Acute expansion of the hematoma was significantly increased with the severity of liver dysfunction and history of heavy alcohol drinking. The levels of glutamic oxaloacetic transaminase (GOT), alkaline phosphatase, gamma-glutamyl transpeptidase (gamma-GTP) and platelet (PLT) count were meaningful indices of hematoma expansion.